Rob Huff is a seven-time race winner in the World Touring Car Championship, and has been a factory Chevrolet driver since 2005.
Jolyon Palmer - son of former grand prix driver Jonathan - is leading this year's Formula 2 championship with four wins from 10 races so far.
Huff hasn't raced a single-seater since his Formula Renault campaign of 2001, while 19-year-old Palmer's only prior tin-top experience was in T-Cars at the beginning of his career.
Ahead of this weekend's WTCC and F2 rounds at Brands Hatch, the pair tried out each other's cars in a test on the British circuit's Indy layout.