Comparative, I believe, as the red and blue cars are being used a single entity, so to speak.

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Well aparrently red and blue are faster then the yellow car, so if your point is to say that those 2 out of 3 are the fast ones you use faster.

But if you say that the blue one is faster then yellow and the red one faster then blue then of course red is fastest.

Faster. Fastest Doesn't sound right.

Actually, Fastest is used when comparing more than 2 entities, but when 3 entities are used and 2 are being used against the leftover one, the 2 entities become one for the duration of the comparison.

In other words, faster is only used when the fastest is ambiguous.

okay, that makes no sense, and it's probably wrong.

Faster then.

Or you could always say "the yellow car is slowest."

-Nikira

Or you could simply re-word the sentence: "the red and blue cars are faster than the yellow one". That sounds more natural, in my opinion.

Out of the red, blue, and yellow cars, the red and blue are the fastest?

But yeah for your context, I'd used faster.

It's proper either way.

-=< >=-

Whichever version is most popular wins.

Whichever version is most popular wins.

In other words: better as a poll?

=P

Whichever version is most popular wins.

Truthiness?