It seems to me, though, that there must be SOME good (or goodish) motor sport fiction, and I'm nominate three for starters.

A book for teenagers, it starts at a pre-war Around-the-houses race meeting at Albany, Western Australia (and I was amazed to read about it in a novel!), and concludes at Brooklands. One of the characters is recognisably derived from larger-than-life Western Australian motor sportsman Aub Melrose.

I don't think Hawthorn wrote this, but his ghostwriter is unknown. One of two books for kids featuring the teenage Carlatti and his adventures in mid-50s GP racing.

A modern day thriller which revolves around a scandal in the 1909 Peking to London race. The race is imaginary, of course, but the racing background is pretty good.
None were going to win the Nobel Prize, but all were a pretty reasonable read, and you don't cringe at the author's motor sport technicalities.