Transportation and Vehicle Safety: fuel consumption, operational parameters, fuel consumption

Question
Which one will use more fuel... Driving the car (Ford torrus 1991 model) for one hour OR Just switch on the car(ie keeping the car started)to warm up for one hour. If there is difference in the fuel consumption between these 2 situations, i am also curious to know how much difference will be there. Looking forward to hearing from you.
Thanks in advance.

Answer
Hi Jabs and welcome to AllExperts....

an idling motor always uses more gasoline than reasonably driving it. The engine is most efficient when driving within it's operational parameters (2000-4000 RPM  /-) under it's design load.

Also, warming an engine, even in -20 below zero, should only take 5 minutes. Hope this helps!

Terry