The Lotus 42 was an Indianapolis racing car for the 1966 season. It was development of the succesful Type 38 car. The aluminium monoque chassis was designed around the proposed 4.2 litre flat 16 BRM H16 engine with 650bhp. The car had problems when tested at Snetterton. So for the 1966 season, the Type 38 was used with great success. The Lotus 42F was an attempt to make the 42 successful for the 1967 season. It had a revised chassis and different engine; the Ford Quad cam V8. The second car, raced by Graham Hill, suffered engine problems and development of the Type 42 was halted.

The Lotus 42B was originally designed as an Indianapolis car but would do most of its racing in F5000. The 'B' does not indicate a revised design, it stood for BRM. Like the sister design, the F1 Lotus 43, the Indy 42 was intended for the BRM H16 engine, this time in 4.2-litre form. Designed by Maurice Phillippe, the two chassis were built for the 1966 season but mothballed when the BRM engine project stalled. Even when the H16 did appear, it was massively overweight and blew up after just two laps of testing. The project was scrapped and the only 42 to be shipped to America for the 1967 Indy '500' was quickly fitted with a Ford V8. Graham Hill, the 1966 Indy '500' winner, drove the renamed '42F' but retired after 23 laps. Neither 42 would be run by Team Lotus again. After the '500'. the unused second car, now designated 42B/2, proved hard to sell and eventually passed to Dave Lazenby's Lotus Components Ltd. From there it would be sold via Robs Lamplough to Bill Brack for 1969 Formula A. The 42F remained in the US and stuck around even longer, eventually going to Brack as a show car.