Not definitive but interesting
I've no useful evidence to add to your study but
can offer 4 suggestions:
1) try to factor out effects of manufacture and car
models - get data for different coloured cars of the
same model, model year and equipment level. Adjust
for mileage differences.
2) which car was in motion during the accident - both or
just one - which coloured one(s)?
3) Which coloured car(s) was in view or not in view of
the other drivers in the accident?
4) factor in whether there is a difference in human
depth and / or motion sensitivity when subjects view
objects of various colours. If your results are
meaningful, it may be that silver colour objects are
perceived as being closer and / or in motion more so
objects of other colours.
My car is silver.
Competing interests: No competing interests