[Formerly Steve Wilkinson]

There have been endless discussions of this, and you can do searches, but here's what I'd do if I drove my 911 in cold weather (which I don't) and didn't have a garage (and yes, I don't have a garage; I put the car in the barn for the winter).

For years, I flew airplanes in the winter, and light airplanes have flat, air-cooled, four- and six-cylinder engines in many ways very similar to those in 911s. And at least as expensive.

Those of us who did this had a variety of ways to preheat the engines before we started them--everything from lightbulbs under the cowling to magnificently heated hangars. But the most effective way proved to be a six-inch-square rubberized heating element that we epoxied to the flat base of our Lycoming's or Continental's sump, and put on a timer so that it started heating at, say, three in the morning if we had an 0900 takeoff scheduled.

By the time we got to the airplane, the entire engine--oil, sump, crankcase, crankshaft, cylinder barrels, pistons--would be warm to the touch. Okay, tepid in some places farthest from the heating element, but at least equivalent to an engine being started on a 70-degree day in the summer.

These heating elements cost $150-$200 at aircraft supply houses such as Aircraft Spruce and Wicks, and you could simply plug one into an extension cord in your driveway. They're absolutely safe because they have to be FAA-certified and are thermostatically controlled: they heat to about 170 degrees and then cycle off and come back on when the temp drops to 160.

Buy one, attach it to your sump.

Do NOT attach it to your oil tank, even though that's a much flatter and easily accessible surface. You don't want to heat the oil--which will chill right back down to zero the minute it's pumped into the bitter-cold engine--you want to heat the block. Don't let anybody tell you different, because trust me, if they do they have never dealt with an airplane engine.