If I had a leased vehicle and ran whatever the dealer put in the car, I would start and just drive away. Since I don't and own ours, I like to give them a little time to get things circulated. During winter, that could be from 2 to 4 minutes to scrape off windows and clear windshield fog. In the summer its probally 30 seconds and then its business as usual. A neighbor lady of mine starts her SUV up stone cold and drives away like she is 10 minutes behind schedule everyday. She changes vehicles quite often so probally doesn't care.