Name of a card trading game
The description of play sounds like Top Trumps, but I'd never seen a cars version.
Wikipedia confirms the existance of car-based packs:

Top Trumps was a card game popular with adults and children in the United Kingdom in the 1970s and 1980s, especially amongst boys, for whom it was a popular playground pastime. The topics tended to reflect this, and included military hardware, modes of transport and racing cars. The packs tended to be priced so that children could collect new packs by saving pocket money for a few weeks.
The original Top Trumps were launched in 1977, with eleven different packs published by a company named Dubreq. Dubreq was also known for the Stylophone. Dubreq was taken over by Waddingtons in 1982, and they continued manufacturing packs until the early 1990s. The packs from this period are now collectible.[2]

The game having been relaunched in 1999 with new packs by a new company, the same mode of play is available.