PD-4501 Scenicruiser

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PD-4501 Scenicruiser
Scenicruiser Greyhound.jpg
Greyhound ad showing a Scenicruiser
Manufacturer GMC
Production 1,001 units
Body and chassis
Doors 1
Floor type Aisle with raised seat platforms on each side
  • Two 4.7L (281 ci) GM 4-71 I4 diesel (1954-1960)
  • 9.3L (568 ci) GM 8V-71 diesel V8 (after 1961)
  • One 3-speed manual + 2-speed auxiliary gearbox (1954-1962)
  • 4-speed manual (starting in 1961)
Length 40 feet (12.19 m)

The GM PD-4501 Scenicruiser, manufactured exclusively for The Greyhound Corporation, was a three-axle monocoque two-level coach used by Greyhound from July 1954 into the mid-70's. 1,001 were made between 1954 and 1956.

The Scenicruiser became an icon of the American way of life due to its presence throughout the USA in cities and along highways and popularity with the traveling public.

The high-level design concept of Scenicruiser resembles some of the rolling stock of the passenger-carrying railroads of the United States and Canada, particularly their popular stainless steel dome cars. This type of two-level motorcoach body was common in the late forties in Western Europe, including Great Britain where it was known as Observation coach.[1]

The concept of two-level monocoque body had been used earlier in the Spanish Pegaso Z-403 two-axle coach, designed in 1949 and entered production in 1951.[2]


The Model PD-4501 as GMC called it was the most distinctive American parlor bus design of the modern era. It was the result of seven years of effort by Greyhound and GM Truck and Coach Division. The first GX1 prototype was based on a design by Raymond Loewy as U.S. Patent 2,563,917. Originally conceived as a 35-foot (10.67 m) bus, Greyhound later used a tandem-axle, 40-foot (12.19 m) prototype called the GX-2, also designed by Raymond Loewy, to lobby for the lifting of length restrictions that applied to the operation of buses longer than 35 feet in most states at the time.

Power for the production models was originally provided by two GM Diesel 4-71 engines of 150 HP each connected by a fluid coupling because GM had never seen the need for a V8 version of its Series 71 diesel engine. Each coach had a single three speed manual transmission with a two speed splitter for six forward speeds. There were some problems when the coaches were new because all of Greyhound's other coaches had four speed manual transmissions that shifted differently than those in the Scenicruiser. This meant additional training for drivers, who mostly disliked the new system. Interestingly enough, This rebuilding started during October so it was not the first use of GM's 8V-71 engine in a coach. The first coaches to use this engine were 1961 NEW Silver Eagles made for Continental Trailways by La Brugeoise et Nivelles (now part of Bombardier) in Belgium. The 1960 models of this coach used Cummins NRTO engines. When the 8V-71 was announced the 1961 models were shipped to Houston without engines and the 8V-71's were installed there. This started shortly before GM's model PD 4106 was introduced. Late in 1961 Eagle production was moved to the new Bus & Car factory (the coaches were now known as Model 01 Eagles) and Continental started shipping the engines to Belgium for installation in the coaches on the assembly line.

The first design prototype for the Scenicruiser, called GX1, was a double decker with access from the lower deck and the driver was seated on the upper deck. It was soon decided that a split-level design would be better because the GX1 was too tall for many Greyhound garages and lacked luggage space for 50 people. The GX2 had a lower level containing the driver's area and entrance with 10 seats plus a restroom on the driver's side and the upper level with 33 more seats. This arrangement also allowed a large baggage compartment underneath the second level and provided a 360-degree view from the upper level. This was called the GX2. Both the GX1 and GX2 were actually built by Greyhound in 1947 and 1949 with help from GMC. In late 1953 GMC started work on its first prototype called the EXP 331. It was completed in 1954 and had some unique features that were not used on the production versions. Interestingly enough. After the last PD 4501 was built, this prototype was rebuilt by GMC and left the factory with serial number PD 4501-1001. The Scenicruiser was equipped with air-ride suspension and air-conditioning. The coaches were also unusual in having 10 wheels. Each rear axle had four wheels and tires but only first one of them (seen from the front) was a driven axle.

The Scenicruiser's popularity with the public inspired GM's later PD 4107 and PD 4903 Buffalo bus 35 and 40 foot models, which arrived nearly a decade later. They had a less obvious "second level" which ran most of the length of the coach, side windows from GMC's line of transit coaches and a smaller upper windshield in the front because the driver and first passenger seats were positioned higher. Unlike the Scenicruiser, these models were available for sale to all operators. The Scenicruiser also caused GMC's top competitors, Flxible and Beck to bring out similar offerings. Flxible introduced the semi deck and a half Vista-Liner 100, a 35 foot coach (208 produced between 1955 and 1959) and Beck produced three similar 35 foot coach models for a total of 29 coaches. Beck also built twelve 40 foot Scenicruiser lookalikes in 1955 powered by the 300 HP Cummins NHRBS diesel engine. They were Beck's model DH1040 and some were delivered new to Queen City Trailways (later Continental Southeastern Lines). Most of Beck's 40 foot coaches were sold to operators in Cuba and Mexico. Beck had to repossess several of them and they later returned to the United States and were resold as used buses. A number of Vista-Liner 100's and even at least one of the later Becks have been converted to motorhomes and are still on the road. Mack Truck and Bus also produced a single model MV-620-D prototype in 1957 that was also 40 feet long but it found no takers even though Greyhound leased it for several months. This coach still exists in private hands in Ohio.

Problems and effects on the North American bus industry[edit]

As introduced, the Scenicruiser had some significant problems, particularly the drivetrain and cracking of the frame structure around the side windows in the rear quarter of the coach. GMC was not about to put a non-GM engine into its flagship coach nor was it willing to create an V8 version of its Series 71 diesel engine at the time even though it certainly had the resources to do so. That meant GM's only solution was to use a pair of 4-71 engines. Initially

Maintenance on the Scenicruiser was a constant headache – partly because of the complicated nature of some of the new systems (in the manner of Rube Goldberg, some of the critics suggested), partly because some of the components were too new and unimproved (using new, unproved, and unimproved technology), partly because the diagnostic tools and techniques were inadequate, partly because the training and availability of mechanics (and maintenance supervisors and managers) for the new model were less than optimum, partly because the technical support and repair-parts support were less than optimum, and largely because of a combination of several of those factors – along with a few other explanations – including, sadly, occasional incidents of careless or intentional abuse of the new coaches by disgusted drivers or mechanics.[3]

GMC solved one major problem in the factory as the 1955 models were being produced. The original clutch was electrically rather than mechanically operated. That meant the drivers could not make the clutch smoothly engage; it was either in or out. This caused lurches and jolts every time the driver started from a stop or changed gears and both passengers and drivers didn't like it. The electrical linkage was replaced by a mechanical one which solved the problem. GMC gave Greyhound enough sets of parts to convert all of the previously made coaches. At the same time the windshield wipers were changed to a pantograph design which kept them in full contact with the glass at all times and this was also retrofitted to older coaches. The other problems were mostly solved starting in 1961 when all 979 Scenicruisers were rebuilt, which cost Greyhound over 13 million dollars.

The problems with the Scenicruisers greatly soured relations between Greyhound and GMC. Greyhound continued to buy GMC coaches with the PD 4104 up through 1960 and the PD 4106 from 1961 to 1964. Given the problems with the PD 4501, Greyhound had no interest in asking GMC to produce a second version of its signature coach based on the PD 4106's mechanicals and styling. Greyhound also bought some "Buffalo" buses from GMC, also known as the model PD 4107. Greyhound bought 362 of these buses in two orders (162 in 1966 and 200 more in 1967, with the 1966 units being trouble prone) and never bought another GMC coach afterwards. In 1958 The Greyhound Corporation had bought a controlling interest in Motor Coach Industries (MCI), Limited of Canada and in 1961 acquired full ownership of it which led to the end of its need for GMC coaches after MCI reached full production in 1968. GMC's sales soon went into terminal decline as both Greyhound and Trailways were building their own coaches.

Beck left the bus and coach market in 1957, a year after being taken over by Mack. Mack left the bus and coach market in 1960 except for a short time as an importer of rebadged Renault FR1 coaches between 1986 and 1989. Flxible built its last intercity coach in 1969 and last transit coach in 1995. GMC left the new coach market after producing the 1980 models and continued transit coach manufacturing until 1987.

Companion Model[edit]

GMC also introduced its model PD 4901 in 1954 so as to have a 40 foot model to sell to non-Greyhound operators. It was mechanically identical to the Scenicruiser but the driver and passengers were all at nearly the same high level as the Scenicruiser's upper deck. Like the PD 4104, the PD 4901 had a flat floor so the seats were a few inches lower than in the PD 4501 and this allowed taller overhead baggage racks The only one produced was clad in gold anodized aluminum paneling and GMC called it the Golden Chariot. No bus operating company in the country wanted to take on the additional complexity and fuel consumption of this dual engined model and none were ever ordered by any American coach operator. The fact that Greyhound's troubles with its Scenicruisers were already well known was enough to keep potential buyers away from it. GMC leased it first to Greyhound and then to several other smaller carriers in the northeast and finally sold it as a used bus. This coach is currently owned by Wilson Bus Lines in Massachusetts who want to restore it to its former glory.

Super Scenicruiser[edit]

In 1961 and 1962 Marmon-Herrington rebuilt the existing Scenicruiser fleet for Greyhound, 22 having already been totaled in accidents. The rebuild included installing the newly-available Detroit Diesel 8V-71 engine and a 4-speed unsynchronized Spicer manual transmission in place of the twin 4-71 engines and 3-speed transmission with 2-speed splitter. Another change was adding side reinforcement plates above the rear wheels and below the upper deck windows under the skin. The interiors were also freshened up but this was done by Greyhound. After the rebuilding the Super Scenicruiser name replaced the Scenicruiser name on the sides of each coach.

In spite of the rebuilding, the cracking problems continued and the Scenicruisers that made it into the 1970s again had some external trim panels removed and further reinforcements added.


  • Length: 40 feet (12.19 m)
  • Width: 96 inches (2,438 mm)
  • Height: 131 inches (3,327 mm)
  • Wheelbase: 261 inches (6,629 mm)
  • Turn radius: 45 feet (13.72 m)
  • Powerplant:
    • 1954: 2x GM Diesel 4-71 engine
    • 1961-62 repowering: 1x Detroit Diesel 8V-71 engine
  • Transmission: manual, Spicer, 3-speed with 2-speed splitter originally (6 speeds altogether), Spicer 4-speed after repowering
  • Fuel Tank: 180 US gallons (150 imp gal; 680 L).
  • Seats: 10 on lower level, 33 on upper level. Total 43 seats
  • Luggage: 344 cu ft (9.7 m3).
  • Aisle width: 14 inches (356 mm)
  • Front door width: 26 inches (660 mm)

Survival and sequels[edit]

About 200 Scenicruisers were still in service when Greyhound withdrew them around 1975. As of 2015, some of these remain, many converted to motorhomes. Other owners are committed bus enthusiasts who have restored their buses to like-new condition. A number of them were bought as used buses and ran in the colors of their new owners for some years after leaving Greyhound. A few even ended up wearing Trailways red and white as they were bought by Trailways affiliate carriers.

The influence of the Scenicruiser may be seen in General Motors' 1964 Buick Sport Wagon and Oldsmobile Vista Cruiser station wagons, both of which had stepped-up roofs and a raised skylight over the second row of seats.[4][5]

Literary references[edit]

The Pulitzer Prize-winning novel A Confederacy of Dunces, by John Kennedy Toole, includes many obsessively sarcastic references by his main character to a trip in a Scenicruiser coach, which he recounts as a traumatic ordeal.


  1. ^ Whitson RC35C built on Maudslay, Leyland, AEC, and Foden chassis between 1949 and 1952 (accessed March 10, 2013)
  2. ^ Pegaso Monocasco (monocoque) brochure 1951 accessed March 10, 2013
  3. ^ Duncan Bryant Rushing. "Bluehounds and Redhounds, the histories of Greyhound and Trailways". Retrieved 7 May 2011. 
  4. ^ HowStuffWorks.com article mentioning possibility of 1960s GM station wagons being inspired by Scenicruiser Retrieved 2011-06-18
  5. ^ Eric Peters Autos page citing possible Scenicruiser heritage for the Vista Cruiser Retrieved 2011-06-18

See also[edit]

External links[edit]