I’ve had a second and third look at what you've done and it’s brilliant!
A couple of minor
comments on layout, which may have been forced on you by the database logic
1. Race Title
As Don Cappswould say, I’m flogging a pallet of canned dog food here, but I suggest
On the index "French Grand Prix"
On the page “Grand Prix de l’ACF (French Grand Prix)”
or even “Grand Prix de l’Automobile Club de France (French Grand Prix)"
2. World Championship races
Why not do them in bold on the index
or say “World Championship Round 3 – French GP”
I see no need for anything on the page
3. Shared drives
I think this could be shown better, but appreciate the constraints imposee by the database. How about:
Alternative 1 – Charles Pozzi/Georges Grignard in the driver’s name. Or will this compromise searchability?
Alternative 2 – Do it as a ‘Note on the cars’. Conveys the information but compromises the purity of presentation.
Alternative 3 - Under "Place" put the placing in the box for the first-named and a blank or underscore [_] in the second. Or does this foul up the sort function and spoil searchability?
UnderTime/speed, put ‘Shared drive’ only for the second name allowing you to put the time for the first:
2 Alberto Ascari Ferrari etc 80 2h 51' 49.7
_ Dorino Serafini Ferrari etc 80 Shared drive
4. DNS, DNP, DNA
I like the different categories. Is it worth adding a reason if known, e.g.
DNS – Practice crash
DNS – engine failure in practice
DNA – Transporter hi-jacked by Bjorn ;)
5. Missing and ambiguous data
I didn't see any, but you can always say "Not known" put (tentative) after something
And finally, a couple of queries/omissions:
British GP – who shared which ERA E-Type with whom? There's something wrong with what's shown
Daily Express International Trophy – Heat 2 results are missing?
Jersey Road Race – Notes 5 and 8 are the same why not just say ‘See Note 5’ on both results. Or does that mess up database searchability?