Ogilvie and Rudd reasoned that to take a further step ahead of the competition, the new car should be designed as one huge ground effect system, starting just behind the nose and extending all the way to the back of the car beyond the rear wheels.
An additional ground effect system was built into the nose, in an effort to turn the whole chassis into an aerodynamic device. In theory this would create a tremendous amount of downforce, so the chassis would have to be built to be more structurally rigid than the Lotus 79s. The 80 also would not need wings due to the massive downforce. Chapman approved the idea at once.
The car appeared resplendent in British racing green, since John Player Special had pulled out of F1. The car featured 'coke bottle' sidepods, something that would become familiar in the 1980s. However, a serious problem was encountered during testing. Mario Andretti reported that at speed the car behaved very well, but in braking and cornering, where speeds were lower, the car lost downforce alarmingly then regained it unexpectedly. It was discovered the car was generating too much downforce for the driver to cope with. The problem was twofold: firstly, the ground effect's low pressure area under the car was moving around with the car's centre of gravity. The phenomenon was known as porpoising, as the car appeared to be lifting and squatting at different speeds, causing it to lurch violently through corners. Secondly, the slightest difference in track ride height including off cambered corners, kerbs, etc. affected the undercar pressure hugely. The team experimented by fitting the car with wings, but this had little effect on the way the car behaved. Andretti persevered with the car, but his new team mate Carlos Reutemann refused to drive it and stayed with the Lotus 79.
Chapman eventually had to admit the 80 was not the wondercar he had planned, and after a reasonable third place for Andretti in the 1979 Spanish Grand Prix, the problems with the Lotus 80 became obvious in Belgium and Monaco. The Lotus 79 was modified and pressed back into service.
It was a massive setback for the team, and for the car which had appeared so promising, however Chapman persevered with the concept of a full length ground effect chassis in the Lotus 88.