Just got back from a July 4th-week road trip from where I live (East SF Bay) to Las Vegas and back. My experience was much like yours, car never broke a sweat in the open desert with 100+ degree temps. and A/C on all the time.
Coincidentally we had a stopover in Barstow on Rt. 66 on the way out. Came back north on the east side of the Sierras and over the Sonora Pass.
The Z16 got lots of approving looks and smiles from folks on the Strip, and those mountain roads were just too much fun.
