Hope Misty turns up soon, I do so agree with you Madmax in that it is the knowing that hurts the most! xx
if you haven't already done so (though I hope & will continue to hope that she is absolutely fine & as I say, just holed up somewhere, out of the weather!), it might be an idea to 'phone round/call in at the various vets surgeries in the area, not just to check that she hasn't been brought in but to leave a poster.
Start local & expand the radius as you go on, many people involved (for example only, don't panic!) in an RTA with an animal don't always (even in this day & age of mobiles, sat navs etc.) go to the nearest vet, they go to their own vet, which can sometimes be a fair distance away.
Try the local branch of Cats' Protection as well, they can be tricksy to get hold of but don't be put off by a branch contact number a fair distance away, they nearly always have local contact numbers as well. Google any/all smalll local charities & if not convenient to visit in person, ask if you may email them a copy of your poster for reference.
Any local livery stables might also be worth taking a poster round to & asking to put it up in their tack room, riders hacking out notice quite a lot of things, even kitties they've never seen before & it just might jog someone's memory.
Ask supermarkets etc. as well if you can put a poster up, or a smaller version of it but always include a picture, people always stop to look at a picture rather than just writing; make the picture as clear as possible & as large as practicable.
(I dislike including the local council in any contact list but in worse case scenarios, most do keep a log of RTAs.)
Lastly, make a note of everywhere you left a poster & when Misty returns, try & go round & remove each one (apart from vet surgeries or where you've emailed info., where a 'phone call will suffice), it makes people much more repsonsive next time if they get thanked & told of the outcome, rather than leaving a tatty poster up for months afterwards, or an unresolved note in a diary somewhere.
Hopefully the little miss will come strolling back however, acting as though nothing had happened! xx