Just bought at 2006 E350 4Matic with 27K miles 2 weeks ago and now second owner. What is the recommendation for warming up the car in cold temp's? (Philly area) My background is heavy duty diesel engines where we apply jacket water / lube oil heaters, battery heaters etc. for quick start.

The car has neither but would like to know if there's anything wrong with warming up the engine until the interior heater shows some heat?

Second, I also hear mix opinions on hi-test gas vs. using regular gasoline. Any strong opinions on not using hi-test?