Drive it forever
Q. I have a 1999 Audi A6 Quattro with 112,000 miles. The heater blows cold at idle, but blows hot when I have my foot on the gas. The coolant reservoir is full, the fans work, there are no signs of leaks, the dashboard gauge reads normal, and the water pump and thermostat check out fine. What's up?
A. Does the heater really blow cold, or does it blow lukewarm, as in not hot enough to keep you warm?
You say this problem happens only at idle, not on the road. If the air is truly cold, as in outside-the-car cold, either there's something awry in the plenum, and outside air is making its way in without being heated at all, or the heater core is plugged.
I doubt that either is the case, though. If you're simply getting air that hasn't been warmed enough, that's the way it is in some cars. The water pump does not route enough hot coolant through the heater core to heat the interior at idle. Why not? The water-pump capacity is high enough to keep the engine cool at wide-open throttle, and a high-revving engine simply doesn't spin the pump very fast at idle.
My suggestion is to use recirculate mode, so you're reheating lukewarm interior air instead of fresh, frigid exterior air. Running the fan at low or medium will let the air passing through the heater core gain some temperature. If you do this, the air coming from the vents will be warmer.
Q. We read numerous stories about the benefits of E85 fuel for cars, and I would like to use it, since it is becoming more available. But the service manuals for my 2003 Acura and 2007 Hyundai both state to use no more than 10 percent alcohol content in fuel. Are there any fixes being produced to utilize this fuel that won't violate the warranty?
If not, it's all hot air and useless effort, as there are hardly any cars on the road that can employ its pollution-reducing benefits.
A. No carmaker provides a kit to change a vehicle over to FFV (flex-fuel vehicle) status.
E85 cars have corrosion-resistant fuel systems with upgraded plastic and rubber parts, plus a fuel sensor that can determine the proportion of ethanol to gasoline. The fuel-injection computer, different from the one used in non-FFVs, can then inject the correct amount of fuel. This is necessary because it takes a larger volume of ethanol to run your engine than you need with straight gasoline.
There are aftermarket kits, but they do not use this sensor and can only trim fuel-mixture ratios by using the oxygen sensor, which I think isn't adequate - and neither do the car manufacturers, or they would have done it this way and saved the cost of the sensor.
My suggestion is to go to www.epa.gov and look up what vehicles on the market are already available as FFVs, then buy one of them. According to the National Ethanol Vehicle Coalition, there are 6 million cars on the road that are E85-capable.
Dear readers: Here's the scenario. You get into your car, you try to start it, and the ignition key won't turn the lock cylinder. You try again, this time twisting the key hard enough to worry about breaking it off. Nothing doing. Time to call a tow truck. Right?
Wrong. There's no problem. You simply shut off the engine while holding a little torque on the steering wheel, which left the front wheels a bit skewed. When you took the key out, the locking pin slid home, the steering column tried to straighten itself out, and that put pressure on the locking pin, which made the key hard to turn.
To relieve that pressure, simply wiggle the wheel back and forth an inch or two while you gently twist the key. This will unload the pin, and off you'll go.
Mike Allen is a senior editor for Popular Mechanics magazine. Questions should be sent via e-mail to driveit@nytimes.com. 
