The Lotus 86 was another attempt to harness "ground effect". Instead of having a rigid chassis with sliding skirts, the idea was to have a "dual chassis". The internal chassis would remain fixed, while the external chassis would move and create the nessessary downforce. Unfortunately during testing sliding skirts were banned in Formula 1, which led to a halt on the Lotus 86. In the meantime the Lotus 81 was used until the Lotus 88 (a tidier and lighter version of the Lotus 86 with no sliding skirts) could be completed.
Team Lotus 50th Birthday, Hethel Test Track, August 2004