Warming up a car engine

this passed along to me by my pal, cap'n happy -- i don't know his
source.
my rule of thumb on the continual car is idle until the engine RPM
naturally kicks back (it's about 10 seconds).
i also let it idle at all stop lights and intersections, but shut it
down (continually) in things like drive-thrus.

{4/28 -- this came from fortune magazine}

***

"In the past, when cars had carburetors, engines used thick oil that
required warming up," says Mike Harrison, Ford's V-8 engine programs
manager. Today's thinner oils allow engines to be driven away sooner,
making
idling unnecessary.
His rule: If you're operating your car above 0° F, you can drive away
within
10 seconds (he advises 30 seconds for temperatures below zero).
Experts also say you'll save gas by turning off your engine if you're
going
to idle for more than 30 seconds -- some studies suggest even less
time.
According to an EDF report published last year, unnecessary idling will
waste between $44 and $392 on fuel annually (range depends on fuel
prices,
idling habits, and vehicle type).
But won't shutting the car on and off wear down the starter and battery?
Two
extra restarts each day will average about $10 a year in repairs. "If
your
engine is operating fewer hours, there's less wear on the most
expensive
parts," says Jeff Bartlett, an auto editor with Consumer Reports