The Lotus 38 was the first mid-engined car to win the Indianapolis 500, in 1965, driven by the great Jim Clark.
It was run by Lotus at Indianapolis from 1965 to 1967; a total of 8 were built, most for use by Lotus, but several were sold for use by other drivers, including A. J. Foyt and Mario Andretti.
It was designed by Colin Chapman and Len Terry as Lotus' 1965 entry for the Indianapolis 500. It was an evolution of the previous Lotus 29 and Lotus 34 Indy designs, but with a full tubular monocoque, and was powered by the same four-cam Ford V8 fuel injected engine as used in the 34, giving out around 500 bhp. In all of them, the engine was mid-mounted, improving the weight distribution and giving it good handling. The 38 was significantly larger than Formula One cars of the time, but was dwarfed by the massive American roadsters.
The 38 was specially designed with an "offset" suspension, with the car body situated asymmetrically between the wheels, offset to the left using suspension arms of unequal length. Although in theory this was better suited for the ovals (which have only left turns), for example by evening out tyre wear between the two sides, in practise the handling was sufficiently idiosyncratic that the concept never caught on widely.
In the 1965 Indianapolis 500, Clark qualified on the first row, and race was a walkover for him, as he led all but 10 laps, and won with only four other cars on the lead lap, and the rest all at least 2 laps behind. It was payback for losing the race in 1963, when Clark felt that Parnelli Jones' oil spewing car should have been black flagged.
Lotus returned with the 38 in 1966 (when it conceded victory to Graham Hill in a Lola, after some confusion with the scoring due to an erroneous lap chart) and 1967 (when Clark retired early with a blown engine).
The 38 had proved that mid-engined cars could make the grade at the Brickyard, and the days of the front-engined roadsters were effectively over. Design elements in the 38 were eventually worked into the design of the legendary Lotus 49, and Foyt's early Coyotes (as well as a number of other contemporary Indy cars) were Lotus 38 clones.