That poor baby. 20 minutes is a long time for any dog breed to be left in a hot car, but espically a small dog such as a yorkie. My mom went in grocery shopping once around mid-june and was in there for about 45 mins while Chloe stayed in the truck (now three things, my mom didnt know she would be gone so long, where i live everyone knows everyone and is close, and the doors were locked) when she came out Chloe was panting so my mom took her up and she basically went limp. My mom freaked out and got her water right away. After that incident we never brought her along if she was going to be left alone in the truck on hot days. Scary stuff.