Sorry guys....but a simple google search reveals FAR MORE pundits backing the 30 seconds and you are good to go theory. Yes, many touch on the different metals and such that comprise an engine, but as long as you aren't putting your foot down, you will warm the car much faster driving it and therefore, bring the entire engine to temp faster. Just be cautious with your gas pedal. I'll keep motoring along like this (as I have for the past 20 years). YMMV of course.
https://ca.autos.yahoo.com/blogs/green/8-facts-myths-warming-car-winter-201000465.html