I'm on the verge of finalising a deal on a RX-8 and I'm wondering if I should wait for a brand new car or take the new one that sat in the lot for about 2 weeks.
The thing is that I've been waiting for a week for the snow in my area to go away (still -11C at night here so all the sidestreets are literally ice rinks), and while I'm waiting, the car's been sitting in the lot at tempreatures reaching -16C at night and then above freezing during the sunny dayt time for a week. Would this do enough REAL damage to the car/interior that I should wait another 2 or 3 weeks for a brand new one from the factory?

If this causes real damage then there should be a lot of concerned car owners around the world. Cars are designed to handle temperature those kind of temp ranges.

If you got a good deal going, buy it and enjoy.

how many miles on it?

Ditto - - -

If it's the car you want go for it. Who is to say how long that next car delivered has been sitting at the port of entry. If your looking for a recently produced car look at the build date on the door label (FMVSS is US).

it's brand new, just been sitting in the lot. I put a deposite on it so nobody else touches it =p
I see... yea I guess cars experience that kinda temp. during production testing...
its just that my last vehical a '96 discovery (the one being traded in) had REAAAAALLY bad temp induced problems like how my dash seals shrank and curled from heat and cold.... but I hope that's just crappy workmanship and Mazdas would be way better :)
Thanks for the input guys! :)

Go for it. Plan to get snow tires on it. The standard tires are not meant to even touch snow or cold weather.