Extrapolated from Harrington description:

Each player controls a team of 3 cars. On your turn you assign a movement of 6 to one car, 5 to another and 4 to the third car (on your next turn you may assign the movement allowances differently if you wish).

To add a bit of racing flavor there is the option of slipstreaming (drafting). This is achieved by landing on a space marked with a chevron. If your car is directly behind another car then you may move an additional 3 spaces. If this takes you on to a space offering another slipstreaming opportunity (very rare!) then you may slipstream for a second time (but not a third).

Grand Prix was also published in the compilations of Bertelsmann Buchclub in 1976 (see Jockey & Grand Prix),
and in 1980 by Carlit as part of Spiele-Box .