I am thinking of parking may A6 2.8 for the winter to do repairs such as timing belt and cam seals and using another car untill all that is fixed, could take some time due to the cost of these problems. I will have the car parked in the garage but live in Minnesota and the winters get really cold. Will other problems arise from just letting the car sit in the cold or will it be fine and fire up whenever I want to use it??

 

Well it shouldn't be any problem at all minus the typical problems of storing vehicles for a long period of time (+ cold weather).

If you expect to have freezing temperatures in your garage, you will have to be wary of freezing lines, etc. but for the most part the only thing that might prevent the car from starting up right away would be viscous oil. A less-viscous oil (like 5w-40) will allow the car to start more easily in cold weather.

For further information, just google "storing vehicles over winter" and do what you deem necessary.
http://www.techguys.ca/howto/winter.html
http://www.autotropolis.com/wiki/ind...le_over_winter

I've got my car up here in the Upper Peninsula which has very similar temperatures from Minnesota (i used to live there) except a LOT more snow. Basically there isn't anything special about my car expect for the 5w-40 Full Synthetic oil (which isn't even that special) - typical antifreeze is rated pretty close to -30 degrees F, so that covers that. The oil will let me start the car when it's cold out. Now an important thing to do is to allow the car enough time to evaporate the condensation off of the engine/condenser because otherwise it may build up and cause bigger problems. So if you DO turn it on, keep it on for 15-20 minutes at the minimum before storing it again.