|Suspension (front)||Double wishbone, with inboard coilover spring/damper units.|
|Suspension (rear)||Lower wishbone, top link and radius rod suspension, with outboard coilover spring/damper units.|
Coventry Climax FWMV Mk.II, 1496cc, Crossplane 90° V8
|Transmission||ZF 5DS10 5-speed manual.|
|Notable entrants||Team Lotus
Reg Parnell Racing
|Notable drivers|| Jim Clark
|Debut||1962 Dutch Grand Prix|
|Constructors' Championships||2 (1963, 1965)|
|Drivers' Championships||2 (1963, 1965)|
|n.b. Unless otherwise stated, all data refer to
Formula One World Championship Grands Prix only.
The Lotus 25 was a racing car designed by Colin Chapman for the 1962 Formula One season.  It was a revolutionary design, the first fully stressed monocoque chassis to appear in F1. An early brainchild of Chapman's fertile mind, the original sketches for the car were made on napkins while Chapman discussed his idea while dining out with Frank Costin (designer of Vanwall, Lotus Mk.8, 9, 10, 11 and Lotus 16 bodies, later of Marcos fame), who is the brother of a Lotus engineer Mike (later of Cosworth fame).
The monocoque made the car more rigid and structurally stronger than typical F1 cars of the period. The 25 was three times stiffer than the interim 24, while the chassis weighed only half as much. The car also was extremely low and narrow (frontal area only 8.0 ft², 0.74m² compared to the normal 9.5 ft², 0.88 m²)It was also envisaged to have a column gear lever, to keep cockpit width to a minimum, although this was only experimental and discarded. To assist this, the driver reclined sharply behind the wheel (an idea seen in the 18, and pioneered over a decade previously by Gustav Baumm at NSU), leading to the nickname 'The Bathtub', while front coil/damper units were moved inboard (as in the 1948 Maserati). The 25 was powered by Mk.II 1496cc through to Mk.5 1499cc versions of Coventry Climax FWMV V8 in crossplane and flatplane formats. Later, Reg Parnell Racing in 1964 fitted BRM P56s of similar specification to their second-hand 25s. Such was 25's effect on motor racing, even today's modern F1 cars follow its basic principles.
Some privateers who had been buying Lotus chassis were disgruntled by the fact Chapman refused to provide them 25s. These teams, including Rob Walker Racing, were given Lotus 24s, while the works team had exclusive use of the 25 for Jim Clark and Trevor Taylor. When it first appeared at the Dutch Grand Prix, the futuristic 25 was inspected by John Cooper, who asked Chapman where he had put the frame tubes in the car.
The car gave Clark his first Grand Prix victory, at Spa, that year. He took another win in Britain, and again in the USA, which put him in contention for the title, but at the final race, South Africa while leading, a much publicised engine seizure cost him the title to Graham Hill.
Clark gained his revenge the following year, taking his first world championship in the 25, by winning 7 races, Belgium, France, Holland, Britain, Italy, South Africa, and Mexico. Lotus also won its first constructors' championship. In addition, 25s were entered at Indianapolis, where they trialled Lucas electronic ignition for Ford. The 25 was used during the 1964 season, winning a further three races in Clark's hands. At the final race in Mexico, just as in 1962, the Climax engine developed an oil leak and with literally a lap to run Clark coasted to a halt in sight of world championship victory, this time conceding to John Surtees.
In 2008/9 Lotus launched a special edition of the Elise supercharged model in the original Lotus 25 racing colours. This had track standard sports suspension and traction control. A total of 25 of these Lotus Jim Clark Type 25 cars were produced for the RHD market.
- Automobile Year, No. 10, 1962-1963, Pages 198-199.
- Setright, L.J.K. "Lotus: The Golden Mean", in Northey, Tom, ed. The World of Automobiles (London: Orbis, 1974), Volume 11, p.1230.
- Setright, p.1230.
- Wikipedia, Lotus 18.
- "Chapman was not concerned to be original, merely to be thorough." Setright, p.1230.
- Super Street Cars, 9/81, p.34.
- F1 Facts & Trivia. pp.113 - John White 2007