So vampires shouldn't show up in light that's been bounced off a reflector beforehand, such as most of the beam of car headlights?

No, because that's ordinary photons, reflectors only affect it once it's been reflected from the vampire.

It must be a right bugger to be a vampire cyclist, though. Sorry mate I didn't see you.

This would be distinguishable from being an ordinary cyclist in most places how? (Well, I suppose there might be some justification for using that excuse, but....)

The black cloak and fangs, of course!

Anyone who hits a vampire cyclist with their car probably isn't going to get a second opportunity to do so, though...

This is why I smear my front bumper with garlic pureé.

Ah! I'd wondered about that.

(Or presumably, any sort of garlic would be ok, if you're hitting something as strong as an elephant, the puree should happen naturally :))

Funnily enough, that actually happened in Anita Blake. It's true, she never did again, but she's not dead, so she might one day :)