Lotus Mark IV was a trials car by Colin Chapman built on an Austin 7 chassis.
Chapman's success at building trials cars brought another previous customer, Mike Lawson, to order a second trials car in 1952 to replace his Lotus Mark II, in which he won the Wrotham Cup.
Once again Chapman chose an Austin Seven as the starting point, reinforcing the frame and installing a four-cylinder 1,172 cc (71.5 cu in), Ford, sidevalve engine.
Chapman used all the tricks he had learned in his previous cars, constructing a lightweight aluminium body with a rounded nosecone.
Lawson won his class in the first attempt in this car, following up with others, solidifying Chapman's reputation as a designer and engineer.