Automobile drag coefficient
The drag coefficient is a common measure in automotive design as it pertains to aerodynamics. Drag is a force that acts parallel and in the same direction as the airflow. The drag coefficient of an automobile impacts the way the automobile passes through the surrounding air. When automobile companies design a new vehicle they take into consideration the automobile drag coefficient in addition to the other performance characteristics. Aerodynamic drag increases with the square of speed; therefore it becomes critically important at higher speeds. Reducing the drag coefficient in an automobile improves the performance of the vehicle as it pertains to speed and fuel efficiency. There are many different ways to reduce the drag of a vehicle. A common way to measure the drag of the vehicle is through the drag area.
- 1 Reducing drag
- 2 Deletion
- 3 Fabrication
- 4 Typical drag coefficients
- 5 Drag area
- 6 See also
- 7 References
- 8 External links
The reduction of drag in road vehicles has led to increases in the top speed of the vehicle and the vehicle's fuel efficiency, as well as many other performance characteristics, such as handling and acceleration. The two main factors that impact drag are the frontal area of the vehicle and the drag coefficient. The drag coefficient is a unit-less value that denotes how much an object resists movement through a fluid such as water or air. A potential complication of altering a vehicle's aerodynamics is that it may cause the vehicle to get too much lift. Lift is an aerodynamic force that flows perpendicular to the airflow around the body of the vehicle. Too much lift can cause the vehicle to lose road traction which can be very unsafe. Lowering the drag coefficient comes from streamlining the exterior body of the vehicle. Streamlining the body requires assumptions about the surrounding airspeed and characteristic use of the vehicle.
For high speed applications near or above the speed of sound, a Sears-Haack body, is an idealized shape that minimizes wave drag, which is the drag associated with supersonic shock waves. This shape essentially consists of an elongated tube with pointed ends.
The deletion of parts on a vehicle is an easy way for designers and vehicle owners to reduce parasitic and frontal drag of the vehicle with little cost and effort. Deletion can be as simple as removing an aftermarket part, or part that has been installed on the vehicle after production, or having to modify and remove an OEM part, meaning any part of the vehicle that was originally manufactured on the vehicle. Most production sports cars and high efficiency vehicles come standard with many of these deletions in order to be competitive in the automotive and race market, while others choose to keep these drag-increasing aspects of the vehicle for their visual aspects, or to fit the typical uses of their customer base.
A roof rack is a common trait on many SUV and station wagon vehicles. While roof racks are very useful in carrying extra storage on a vehicle, they also increase the frontal area of the vehicle and increase the drag coefficient. This is because as the air flows over the top of the vehicle, following the smooth lines of the hood and windshield, then collides with the roof rack and causes turbulence. The removal of this part has led to increases in fuel efficiency in several studies.
Mudflaps are now rarely specified as standard on production cars as they interfere with the clean airflow around the vehicle. For larger vehicles such as trucks, mud flaps are still important for their control of spray, and in 2010 a new version of the mud flap was introduced that has been shown to create significantly less aerodynamic drag than standard mud flaps.
A rear spoiler usually comes standard in most sports vehicles and resembles the shape of a raised wing in the rear of the vehicle. The main purpose of a rear spoiler in a vehicle's design is to reduce lift, thereby increasing stability at higher speeds. In order to achieve the lowest possible drag, air must flow around the streamlined body of the vehicle without coming into contact with any areas of possible turbulence. A rear spoiler design that stands off the rear deck lid will increase downforce, reducing lift at high speeds while incurring a drag penalty. Flat spoilers, possibly angled slightly downward may reduce turbulence and thereby reduce the coefficient of drag. Some cars now feature automatically adjustable rear spoilers, so at lower speed the effect on drag is reduced when the benefits of reduced lift are not required.
Side mirrors both increase the frontal area of the vehicle and increase the coefficient of drag since they protrude from the side of the vehicle. In order to decrease the impact that side mirrors have on the drag of the vehicle the side mirrors can be replaced with smaller mirrors or mirrors with a different shape. Several concept cars of the 2010s are replacing mirrors with tiny cameras but this option is not common for production cars because most countries require side mirrors.
While they do not have the biggest impact on the drag coefficient due to their small size, radio antennas commonly found protruding from the front of the vehicle can be relocated and changed in design to rid the car of this added drag. The most common replacement for the standard car antenna is the shark fin antenna found in most high efficiency vehicles.
The effect that windshield wipers have on a vehicles airflow varies between vehicles; however, they are often omitted from race vehicles and high efficiency concepts in order to maintain the smallest possible coefficient of drag. A much more common option is to replace the windshield wipers with lower profile wipers, or to only remove the windshield wiper on the passenger side of the vehicle, and even to fabricate a deflector to deflect the air up and over the wipers.
Another alternative is to equip the vehicle with a single wiper placed in the centre of the windshield, allowing it to cover both sides of the windshield. This mitigates the amount of drag by decreasing the frontal area of the blade. While such application may be useful for racing, for most road vehicles this would produce minimal improvement in overall drag reduction.
The application of new parts and concepts onto the vehicle design are easier to include when in the design stage of a vehicle, rather than in aftermarket (automotive) parts, however, the fabrication of these parts assists in the streamlining of the vehicle and can help greatly reduce the drag of the vehicle. Most vehicles with very low drag coefficients, such as race cars and high efficiency concept cars, apply these ideas to their design.
When air flows around the wheel wells it gets disturbed by the rims of the vehicles, and forms an area of turbulence around the wheel. In order for the air to flow smoother around the wheel well smooth wheel covers are often applied. Smooth wheel covers are hub caps with no holes in them for air to pass through. This design reduces drag, however, it may cause the brakes to heat up quicker because the covers prevent airflow around the brake system. This is why this modification is more commonly seen with high efficiency vehicles, rather than sports cars or racing vehicles.
Partial grille block
The front grille of a vehicle is used to direct air directly into the engine compartment. In a streamlined design the air flows around the vehicle rather than through; however, the grille of a vehicle redirects airflow from around the vehicle to through the vehicle, which then increases the drag. In order to reduce this impact a grille block is often used. A grille block covers up a portion, or the entirety of the front grille of a vehicle. In most high efficiency models or vehicles with low drag coefficients there will be a very small grille already built into the design, therefore a grille block is unneeded. The grille in most production vehicles is built generally to have as much air flowing into the engine compartment in order to keep it from overheating. But most commonly there is too much airflow into the engine compartment, preventing it from warming up in a timely manner, so a grille block is used to increase engine performance and reduce the vehicle's drag.
The underside of a vehicle often traps air in various places and adds turbulence around the vehicle. In most racing vehicles this is eliminated by covering the entire underside of the vehicle in what is called an under tray. This tray prevents any air from becoming trapped under the vehicle and reduces drag.
Fender skirts are often made as extensions of the body panels of the vehicles and cover the entire wheel wells. Much like smooth wheel covers this modification reduces the drag of the vehicle by preventing any air from becoming trapped in the wheel well and assists in streamlining the body of the vehicle. Fender skirts are more commonly found on the rear wheel wells of a vehicle because the tires do not turn and the design is much simpler. This is commonly seen in vehicles such as the first generation Honda Insight. Front fender skirts have the same effect on reducing drag as the rear wheel skirts, but must be further offset from the body in order to compensate for the tire sticking out from the body of the vehicle as turns are made.
Modified front bumper
The front bumper is the first part of the vehicle that the air must flow around. Therefore, it plays a crucial role in reducing drag. A front air dam is often used which extends from the very front of the vehicle down to the lowest part of the vehicle. This is done to direct airflow around and over the vehicle rather than allowing air to travel under it. Contoured deflectors, or tire spats, are often made as part of the front bumper in order to direct airflow around the tire without having any increase to the outward flow.
Boattails and Kammbacks
A boattail can greatly reduce a vehicle's total drag. Boattails create a teardrop shape that will give the vehicle a more streamlined profile, reducing the occurrence of drag inducing flow separation. A kammback is a truncated boattail. It is created as an extension of the rear of the vehicle, moving the rear backward at a slight angle toward the bumper of the car. This can reduce drag as well but a boattail would reduce the vehicles drag more. Nonetheless, for practical and style reasons, a kammback is more commonly seen in racing, high efficiency vehicles, and trucking.
Typical drag coefficients
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The average modern automobile achieves a drag coefficient of between 0.30 and 0.35. SUVs, with their typically boxy shapes, typically achieve a Cd=0.35–0.45. The drag coefficient of a vehicle is affected by the shape of body of the vehicle. Various other characteristics affect the coefficient of drag as well, and are taken into account in these examples. Some sports cars have a surprisingly high drag coefficient, but this is to compensate for the amount of lift the vehicle generates, while others use aerodynamics to their advantage to gain speed and have much lower coefficients of drag.
Some examples of Cd follow. Figures given are generally for the basic model. Some "high performance" models may actually have higher drag, due to wider tires, extra spoilers and larger cooling systems as many basic / low power models have half size radiators with the remaining area blanked off to reduce cooling and engine bay drag.
The Cd of a given vehicle will vary depending on which wind tunnel it is measured in. Variations of up to 5% have been documented and variations in test technique and analysis can also make a difference. So if the same vehicle with a drag coefficient of Cd=0.30 was measured in a different tunnel it could be anywhere from Cd=0.285 to Cd=0.315.
While designers pay attention to the overall shape of the automobile, they also bear in mind that reducing the frontal area of the shape helps reduce the drag. The product of drag coefficient and area - drag area - is represented as CdA (or CxA), a multiplication of the Cd value by the area.
The term drag area derives from aerodynamics, where it is the product of some reference area (such as cross-sectional area, total surface area, or similar) and the drag coefficient. In 2003, Car and Driver magazine adopted this metric as a more intuitive way to compare the aerodynamic efficiency of various automobiles.
The force required to overcome drag is:
As drag area CdA is the fundamental value that determines power required for a given cruise speed it is a critical parameter for fuel consumption at a steady speed. This relation also allows an estimation of the new top speed of a car with a tuned engine,
Or the power required for a target top speed,
Average full-size passenger cars have a drag area of roughly 8.50 sq ft (0.790 m2). Reported drag areas range from the 1999 Honda Insight at 5.1 sq ft (0.47 m2) to the 2003 Hummer H2 at 26.5 sq ft (2.46 m2). The drag area of a bicycle is also in the range of 6.5–7.5 sq ft (0.60–0.70 m2).
|CdA sqft||CdA m2||Automobile model|
|2.04 sq ft||0.190 m2||2011 Aptera 2 Series|
|2.10 sq ft||0.195 m2||2013 Urbee 2|
|2.50 sq ft||0.232 m2||1986 Twike|
|2.54 sq ft||0.236 m2||2002 Opel Eco-Speedster |
|2.69 sq ft||0.250 m2||2009 Loremo|
|2.784 sq ft||0.2586 m2||2010 Edison2 Very Light Car |
|3.00 sq ft||0.279 m2||2011 Volkswagen XL1|
|3.95 sq ft||0.367 m2||1996 GM EV1|
|5.00 sq ft||0.465 m2||2005 Mercedes-Benz Bionic|
|5.10 sq ft||0.474 m2||1999 Honda Insight|
|5.40 sq ft||0.502 m2||1989 Opel Calibra (8 valve)|
|5.58 sq ft||0.518 m2||1993 Mazda RX-7 FD (base model) |
|5.70 sq ft||0.530 m2||1985 Subaru Alcyone/XT/Vortex|
|5.71 sq ft||0.530 m2||1990 Honda CR-X Si|
|5.74 sq ft||0.533 m2||2002 Acura NSX|
|5.76 sq ft||0.535 m2||1968 Toyota 2000GT|
|5.80 sq ft||0.539 m2||1986 Toyota MR2|
|5.81 sq ft||0.540 m2||1989 Mitsubishi Eclipse GSX|
|5.86 sq ft||0.544 m2||2001 Audi A2 1.2 TDI 3L|
|5.88 sq ft||0.546 m2||1990 Nissan 240SX / 200SX / 180SX|
|5.90 sq ft||0.548 m2||2015 BMW i8 |
|5.92 sq ft||0.550 m2||1994 Porsche 911 Speedster|
|5.95 sq ft||0.553 m2||1990 Mazda RX7|
|5.96 sq ft||0.554 m2||1993 Mazda RX-7 FD R1(R2) |
|6.00 sq ft||0.557 m2||1992 Subaru SVX|
|6.00 sq ft||0.557 m2||1970 Lamborghini Miura|
|6.08 sq ft||0.565 m2||2008 Nissan GTR|
|6.08 sq ft||0.565 m2||1989 Geo Metro |
|6.13 sq ft||0.569 m2||1991 Acura NSX|
|6.17 sq ft||0.573 m2||1995 Lamborghini Diablo|
|6.19 sq ft||0.575 m2||1981 Citroën GSA X3 |
|6.20 sq ft||0.576 m2||2012 Tesla Model S P85 |
|6.20 sq ft||0.576 m2||2014 Toyota Prius|
|6.24 sq ft||0.580 m2||2004 Toyota Prius|
|6.27 sq ft||0.583 m2||1986 Porsche 911 Carrera|
|6.27 sq ft||0.583 m2||1992 Chevrolet Corvette|
|6.35 sq ft||0.590 m2||1999 Lotus Elise|
|6.37 sq ft||0.592 m2||2000 Vauxhall VX220 N/A|
|6.40 sq ft||0.595 m2||1990 Lotus Esprit|
|6.41 sq ft||0.596 m2||2003 Smart Roadster Coupé|
|6.54 sq ft||0.608 m2||1991 Saturn Sports Coupe|
|6.57 sq ft||0.610 m2||1985 Chevrolet Corvette|
|6.63 sq ft||0.616 m2||2001 Audi A2|
|6.66 sq ft||0.619 m2||1996 Citroën Saxo|
|6.70 sq ft||0.622 m2||2014 Chevrolet Volt|
|6.77 sq ft||0.629 m2||1995 BMW M3|
|6.79 sq ft||0.631 m2||1993 Toyota Corolla DX|
|6.80 sq ft||0.632 m2||2007 BMW 335i Coupe|
|6.81 sq ft||0.633 m2||1991 Subaru Legacy|
|6.90 sq ft||0.641 m2||1993 Saturn Wagon|
|6.93 sq ft||0.644 m2||1982 Delorean DMC-12|
|6.94 sq ft||0.645 m2||2003 Smart Roadster|
|6.96 sq ft||0.647 m2||1988 Porsche 944 S|
|7.00 sq ft||0.650 m2||2013 Mercedes-Benz CLA250|
|7.02 sq ft||0.652 m2||1992 BMW 325I|
|7.04 sq ft||0.654 m2||1991 Honda Civic EX|
|7.06 sq ft||0.656 m2||2004 Vauxhall VX220 Turbo|
|7.10 sq ft||0.660 m2||1995 Saab 900|
|7.11 sq ft||0.661 m2||1991 Ford Thunderbird LX|
|7.13 sq ft||0.662 m2||1970 Citroën SM |
|7.14 sq ft||0.663 m2||1995 Subaru Legacy L|
|7.20 sq ft||0.669 m2||1995 Nissan Maxima GLE|
|7.34 sq ft||0.682 m2||2001 Honda Civic|
|7.39 sq ft||0.687 m2||1994 Honda Accord EX|
|7.48 sq ft||0.695 m2||1993 Chevrolet Camaro Z28|
|7.57 sq ft||0.703 m2||1992 Toyota Camry|
|7.63 sq ft||0.709 m2||1974 Citroën CX |
|7.69 sq ft||0.714 m2||1994 Chrysler LHS|
|7.72 sq ft||0.717 m2||1993 Subaru Impreza|
|7.80 sq ft||0.725 m2||2012 Nissan Leaf SL|
|8.02 sq ft||0.745 m2||2005 Bugatti Veyron|
|8.70 sq ft||0.808 m2||1990 Volvo 740 Turbo|
|8.70 sq ft||0.808 m2||1992 Ford Crown Victoria|
|8.71 sq ft||0.809 m2||1991 Buick LeSabre Limited|
|8.79 sq ft||0.817 m2||1956 Citroën DS Spécial |
|9.54 sq ft||0.886 m2||1992 Chevrolet Caprice Wagon|
|10.7 sq ft||0.99 m2||1992 Chevrolet Blazer|
|11.6 sq ft||1.08 m2||2005 Ford Escape Hybrid|
|11.7 sq ft||1.09 m2||1993 Jeep Grand Cherokee|
|12.2 sq ft||1.13 m2||1949 Nash Airflyte|
|16.8 sq ft||1.56 m2||2006 Hummer H3|
|17.4 sq ft||1.62 m2||1995 Land Rover Discovery|
|26.5 sq ft||2.46 m2||2003 Hummer H2|
- Physics for Scientists and Engineers, p. 448, at Google Books
- The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains, Volume 1, p. 490, at Google Books
- "First drive review: Porsche Panamera Sport Turismo". Autocar. 2012-12-07. Retrieved 2013-03-01.
- Popular Mechanics Sep 1981, p. 158, at Google Books
- Hoyt, Wade (October 1985). "Shaping up tomorrow's cars". Popular Mechanics: 131.
- "Technique of the VW Beetle". Maggiolinoweb.it. Retrieved 2009-10-24.
- "The Mayfield Homepage - Coefficient of Drag for Selected Vehicles". Mayfco.com. Retrieved 2009-10-24.
- "Volkswagen Cabriolet MK1 Specs". Cabby-Info.com. Archived from the original on 2010-02-05. Retrieved 2010-01-12.
- "Lancia Aprilia Tipo 97 technical specifications". carfolio.com. Retrieved 2012-03-13.
- "1998 SUBARU FORESTER S". theautochannel.com. Retrieved 2010-05-02.
- "Chevrolet Astro Van (1996)". theautochannel.com. Retrieved 2010-05-02.
- "2002 Ariel Atom Specifications". getcarspecs.com. Retrieved 2012-10-12.
- "1995 Ford Aerostar Specs". motortrend.com. Retrieved 2010-08-18.
- "1981 Ford Escort". carfolio.com. Retrieved 2010-05-02.
- "Subaru Forester specs available". CarsDirect. Retrieved 2009-10-24.
- "Evworld Feature: Giving The New Beetle Wings:Vw | Rogers | Beetle | Wing | Drag | Porsche | Volkswagen | Thiokol | Utah | Fuel | Economy | Biodiesel | Diesel | Aerodynamics". Evworld.com. Retrieved 2010-12-07.
- "Aero Testing - Part 3". AutoSpeed. Archived from the original on 21 November 2009. Retrieved 2009-10-24.
- Daily Mail Motor Review 1984
- "Ecomodder Wiki Vehicle Coefficient of Drag". Archived from the original on 2010-04-25. Retrieved 2010-05-02.
- "Subaru Canada". Subaru.ca. Retrieved 2009-10-24.
- Ralf J. F. Kieselbach, Stromlinienautos in Europa und USA, Kohlhammer, Stuttgart 1982, page 19
- "Toyota Celica GT (1995)". theautochannel.com. Archived from the original on 2010-04-12. Retrieved 2010-05-02.
- Smith, David C. (December 1984). "Golf, Jetta much improved and, with them, VWA's hopes". Ward's Auto World.
-  Data as published on the Team website after 2012 Le Mans Race after the addition of rear view mirrors
- "2002 Renault Clio II 1.5 dCi 80 technical specifications and data - 3 door 1.5 litre (1461 cc) S4 79.1 PS - Carfolio.com car specifications pages". Carfolio.com. Retrieved 2009-10-24.
- Ramsey, Jonathon (2009-03-26). "Tesla Model S: Kč970.000 (Kč970.000 (Kč970.000 ($50,000))) EV sedan seats seven, 300-mile range, 0-60 in 5.5s". autobloggreen. Archived from the original on 2009-03-27. Retrieved 2009-04-12.
- "Leichtbau ist nicht das Wichtigste" (in German). Auto, Motor und Sport,.
Da der Smart aufgrund seiner großen Frontfläche von 2,06 m2 einen hohen cW-Wert von 0,35 hat, verbraucht er im Vergleich zum niedrigen Gewicht vergleichsweise viel.
- "Toyota Previa LE S/C 1995". theautochannel.com. Archived from the original on 2010-05-06. Retrieved 2010-05-02.
- "1990 Toyota Previa". carfolio.com. Retrieved 2010-05-02.
- "Nissan Altima GXE (1995)". theautochannel.com. Archived from the original on 2010-05-24. Retrieved 2010-05-02.
- "2002 Nissan Skyline R34 - R34 vs R35". importtuner.com. 2009-10-01. Retrieved 2014-10-01.
- "The Aerodynamics of the Saab Automobiles". Saab History. 2007-04-01. Retrieved 2016-08-05.
- "Saturn SL2 (1995)". theautochannel.com. Archived from the original on 2010-03-28. Retrieved 2010-05-02.
- "Subaru Canada". Subaru.ca. Retrieved 2009-10-24.
- "1995 SUBARU LEGACY L WAGON". theautochannel.com. Retrieved 2010-05-02.
- "1996 Toyota Corolla DX Wagon". theautochannel.com. Archived from the original on 1996-11-28. Retrieved 2010-05-02.
- "Aerodynamics". Le Double Chevron (#59). 1980.
- "Acura Integra GS-R (1994)". theautochannel.com. Retrieved 2010-05-02.
- "2004 Acura RSX Coupe Specs". automobilemag.com. Retrieved 2014-10-01.
- "1964 Giulia 1600 Series 105". conceptcarz.com. Retrieved 2011-06-28.
- "Ford Escort ZX2 (1998)". theautochannel.com. Archived from the original on 2010-06-04. Retrieved 2010-05-02.
- "Ford Fusion specs available". CarsDirect. Retrieved 2009-10-24.
- "1995 NISSAN 200SX SE-R TWO-DOOR COUPE". motortrend.com. Retrieved 2010-05-02.
- "Saturn SL2 (1999)". theautochannel.com. Retrieved 2010-05-02.
- "1990 Chevrolet Corsica Sales training Video". youtube.com. Retrieved 2011-01-15.
- "Review:2003 Toyota Matrix". theautochannel.com. Retrieved 2010-05-02.
- "GM's Korea studio 'broke the mold' with Bolt". Retrieved 2016-09-20.
- "1994 FORD TAURUS GL". theautochannel.com. Retrieved 2010-05-02.[dead link]
- "Honda Civic DX Hatchback (1996)". theautochannel.com. Retrieved 2010-05-02.
- "Honda Civic EX Sedan (1996)". theautochannel.com. Retrieved 2010-05-02.
- Brooke, Lindsay (Nov 4, 2010). "Sweating the Body Details". SAE Vehicle Electrification. Retrieved 2011-11-22.
- "1995 NISSAN 240SX SE SPORT COUPE". motortrend.com. Retrieved 2010-05-02.
- "Nissan Altima GLE (1998)". theautochannel.com. Archived from the original on 2010-04-20. Retrieved 2010-05-02.
- Karel Rosenkranz, Tatra, Autoalbum 2002, page 107
- "Toyota Celica GT-S (2000)". theautochannel.com. Retrieved 2010-05-02.
- "Toyota Tercel DX (1995)". theautochannel.com. Retrieved 2010-05-02.
- "Saturn SL1 (1996)". theautochannel.com. Retrieved 2010-05-02.[dead link]
-  Archived August 4, 2009, at the Wayback Machine.
- "Toyota Tercel Reference - CdA List". Retrieved 2010-07-15.
- "2011 Infiniti G Coupe Specifications". Infiniti USA. Retrieved 2011-01-25.
- "2001 Kia Rio Specifications - View New Kia Rio 2001 Specs & Data at". Internetautoguide.com. Retrieved 2010-04-23.
- "TG meets the Pagani Huayra - BBC Top Gear". Topgear.com. 2012-06-08. Retrieved 2013-04-05.
- "1998 TOYOTA COROLLA LE". theautochannel.com. Retrieved 2010-05-02.
- "Toyota Paseo (1996)". theautochannel.com. Retrieved 2010-05-02.
- "Carfolio Car Specifications". Retrieved 2010-05-02.
- "Four of a Kind: The Alfa Romeo 164 and the "Type Four" Cars". ateupwithmotor.com. Archived from the original on 2011-07-07. Retrieved 2011-06-28.
- "AutoZine - BMW 3-Series (F30)".
- "1996/1997 FORD TAURUS SHO". theautochannel.com. Retrieved 2010-05-02.
- "1996 FORD TAURUS GL SEDAN". theautochannel.com. Retrieved 2010-05-02.
- gtmash. "Honda Civic CRX - Car Cutaway - Modern Racer - Features". Modern Racer. Retrieved 2009-10-24.
- "2009 Nissan 370Z Coupe Specs". Nissan USA. 2009-08-31. Retrieved 2009-10-24.
- "2003 Toyota Corolla Specs". motortrend.com. Retrieved 2010-05-02.
- "1992 Alfa Romeo 155 1.8 Twin Spark technical specifications". carfolio.com. Retrieved 2011-06-28.
- "AutoZine - BMW 3-Series (F30)".
- http://www.quattroruote.it/news/novita/2015/11/27/fiat_tipo_al_lancio_le_opening_edition_benzina_e_diesel.html. Missing or empty
- "Ford Escape Hybrid". All-about-car-selection.com. Retrieved 2010-04-23.
- "All-new Ford Focus C-Max - Ford Forums - Mustang Forum, Ford Trucks and Cars". Ford Forums. Retrieved 2010-04-23.
- "Nissan Leaf Zero Emission" (PDF) (Press release). UK: Nissan. 2013-07-01. Retrieved 2016-02-25.
- "2000 Toyota Echo Review". theautochannel.com. Retrieved 2010-05-02.
- "Toyota Echo 4-Door (2000)". theautochannel.com. Retrieved 2010-05-02.
- Nate Martinez. "First Test:2013 Ford Fusion". motortrend.com. Retrieved 2014-05-28.
- "AutoZine - BMW 3-Series (F30)".
-  Archived January 20, 2009, at the Wayback Machine.
- Edward Loh (2011-12-02). "First Drive:2013 Subaru BRZ". Motortrend.com. Retrieved 2013-04-04.
- "AutoZine - BMW 3-Series (F30)".
- Interone Worldwide GmbH (2008-06-17). "BMW 3 Series Sedan : Technical data". Bmw.com. Archived from the original on 2009-10-13. Retrieved 2009-10-24.
- "Jaguar XE (2015) technical details and prices confirmed". Car. 2014-10-01. Retrieved 2014-10-15.
- "Mazda Launches Second SKYACTIV Model in Japan: Facelifted Axela".
- "Slippery Tesla Model S triumphs in wind-tunnel shootout". Ecomento. 2014-05-30. Retrieved 2014-10-15.
- "Model X Tesla Motors". Teslamotors.com. Retrieved 2015-12-15.
- Seabaugh, Christian. "2016 Toyota Prius First Drive Review". MotorTrend. Retrieved 2015-11-18.
- Some sources also claim this figure relates to a T87 model test not T77a"Tatra T600 Tatraplan". www.tatraplan.co.uk. Retrieved 2014-08-28.
- Ivan Margolius, 'Model Behaviour', Octane, February 2012, pp. 38-9
- Ivan Margolius & John G Henry, 'Tatra - The Legacy of Hans Ledwinka', Veloce, Dorchester, 2015, page 124
- Optimization and computational fluid dynamics, Gàbor Janiga, Springer, 2008, page 196
- "Cheating Wind - Aerodynamic Tech and Buyers Guide". europeancarweb.com. Retrieved 2008-03-13.
- "Tatra 77 aerodynamic car (czech)". Retrieved 2010-05-17.
- Winning the oil endgame: innovation for profits, jobs and security, Amory B. Lovins, Rocky Mountain Institute, 2004, page 53
- Avion specs, vehicle set the 1986 Guinness World Record for fuel efficiency at 103.7 mpg.
- "50 000 km avec une Citroën Ax diesel, mon avis d'utilisateur ainsi que son coût kilométrique réel". Generationsfutures.chez-alice.fr. Archived from the original on 28 October 2010. Retrieved 2010-12-07.
- Musk, Elon (2016-04-03). Twitter https://twitter.com/elonmusk/status/716751152906440705. Retrieved 2016-04-03. Missing or empty
- "Opel 2002 Eco-Speedster". Retrieved 2015-09-30.
- Frank Giovinazzi (2005-06-14). "Mercedes Bionic Concept Car". Carbuyersnotebook.com. Retrieved 2010-12-07.
- Motor Life-1958
- "Daihatsu UFE-III | Concept Cars". Diseno-art.com. Retrieved 2010-12-07.
- Annoy as little air as possible, Edison2 blog
- "Li-ion Motors Wave II". Li-ionmotors.com. Archived from the original on 2010-12-18. Retrieved 2010-12-07.
- "The Bizarre German Car That Was Ultra-Aerodynamic—And Totally Impractical". Wired. 2014-09-04. Retrieved 2014-10-15.
- Bargmann, Joe (2013-11-04). "Urbee 2, the 3D-Printed Car That Will Drive Across the Country". Popular Mechanics. Retrieved 2014-02-10.
- "D & H Enterprises, composites and fibreglass technology". Dhenterprises.com.au. Retrieved 2010-12-07.
- "TU Delft students build a car with the lowest air resistance in the world". Delft University of Technology. 2015-04-20. Retrieved 2015-04-29.
- "(a bicycle's lower frontal area is offset by a higher drag coefficient)". Lafn.org. Archived from the original on 2011-07-17. Retrieved 2011-06-28.
- "The Mayfield Company Homepage - Coefficient of Drag Tables and Curves". Mayfco.com. Retrieved 2010-12-07.
- "Power Consumption - IGSS'13". Retrieved 2015-09-30.
- McLeod, Mike (2013-05-26). "The Future of Automotive Design?". Design Engineering. Retrieved 2015-09-25.
- "Program: hpvplot (updated 11/12/07)". Ent.ohiou.edu. Retrieved 2010-12-07.
- "Opel 2002 Eco-Speedster". Retrieved 2015-09-30.
- "350 MPGe at $20,000?". Retrieved 2015-09-30.
- "Specs of Mercedes-Benz Bionic Car Concept (2005)". engineact. Retrieved 2013-05-11.