To my knowledge, apart from the blind driving record attempts, the last planned outright World Record attempt was to have been made by the motorcycle team - Maximum Impulse, with the rocket powered Gillette Mach3 Challenger - led by Richard Brown. This was to have been in 1997/1998. After a series of tests and attempted trials the team had to go elsewhere and indeed ended up running on the Bonneville salt flats.
Malcolm, Team Administrator, Gillette Mach3 Challenge by Team Maximum Impulse.