From FinalGear.com Wiki
Star in a Reasonably Priced Car is a segment on Top Gear, where a celebrity is interviewed, then makes a hot lap of the Top Gear test track, for their time to be posted on the lap leader board.
Suzuki Liana
For the first seven series of the show, the car used in the segment was a Suzuki Liana. The car was mainly stock, save for a roll cage, racing harness, and racing seats.
Liana Leader Board
Chevrolet Lacetti
Starting from series eight and beyond, the car was a Chevrolet Lacetti
Lacetti Leader Board
Notes
Leaderboard times literally taken from Wikipedia. [1]