Here is one.
http://animal.discovery.com/breedselector/dogselector.do
I'm not sure on how accurate they are, but here are some sites where you can research the breed it claims is best for you, just to make sure it really is.
http://www.yourpurebredpuppy.com/dogbreeds/index.html
http://en.wikipedia.org/wiki/List_of_dog_breeds
http://www.dogbreedinfo.com/purebred.htm
Its not a good idea to leave ANY dog in a car, even for a little while. That is how some dogs get stolen by passers by, and how many dogs have died from the extreme heat of being trapped inside a hot car.
If you leave the windows down for him or her, a thief can reach in and grab him or her, or if you leave air conditioning on, that will encourage carjackers to break into the running car.
It would be better to take your dog with you and have him or her in a travel crate while in the building with you, that way you'll know that he or she is safe. Let the dog out of the crate and walk around if your allowed to. :0)