The 38 was significantly larger than Formula One cars of the time, but was dwarfed by the massive American roadsters.

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 practice the handling was sufficiently idiosyncratic that the concept never caught on widely.

Foyt had both broken the 160 mph barrier in practice earlier in the month, Clark was the first to do so in official qualifying.

With Parnelli Jones finishing second (also in a modified 34), it was payback for Clark and Lotus losing the race in 1963 when many, including team owner/founder Colin Chapman and journalist/author Brock Yates, felt that Jones' oil spewing front engined roadster should have been black flagged.

Lotus returned with the 38 in 1966, though they conceded victory to Graham Hill in a Lola, after some confusion with the scoring due to an erroneous lap chart, and again in 1967 when Clark retired early with a blown engine.