Q: I recently took a test drive in a 2011 Lexus RX350. Since this car did not have a navigation system, I asked about a backup camera. He indicated that it appeared in the mirror, and proceeded to move the selector from drive to reverse at about 30 mph. The camera came on and there was no change in the rpm or forward motion.

A: That's because the engine management system is smart enough to know that allowing the transmission to engage reverse while moving forward at speed would do the transmission no good at all. The backup camera came on simply because the shift lever was moved to the reverse position.

Hopefully the driver — was he the owner or a salesman?— must have known the transmission wouldn't engage reverse at speed. He was either trying to impress you with his knowledge or if he didn't know, he was a very lucky idiot.

Q: We have a 1993 Chevy Lumina with the 3.1-liter V6. Every now and then the motor will turn over but not start. We wait a few minutes and it fires right up. This happens after we go someplace for an hour or so. Battery cables are clean and tight. I installed new plugs, wires and a new EGR valve. I brought it to our mechanic but he couldn't figure it out. Any help would really be appreciated.

A: The first step is to check for any DTC fault codes stored in the PCM. If none are found, think in terms of fuel pressure and spark — an internal combustion engine cannot start without both of these. Could it be vapor lock, where the ready fuel supply in the fuel rail under the hood is heated to the point that the fuel boils, causing a loss of fuel pressure? Or could it be caused by an overheated ignition module located under the coil packs?

To help the diagnostic process and point your mechanic in the right direction, check for spark with a timing light while cranking the non-starting engine. Also, with a fuel pressure gauge connected to the test port on the fuel rail, run the engine up to full temperature and then monitor fuel pressure bleed-down after shutdown.

If it seems to be a fuel pressure issue, next time it happens cycle the key on for two seconds, then off. Do this six times, then try starting the engine. If it starts, you've confirmed a fuel pressure issue.

If there's no spark, trying cooling the ignition module by misting the area around the module with a spray bottle of water. If this expedites starting, high underhood temperatures may be the issue.

Q: I have a 2007 PT Cruiser with 24,000 miles. I change the oil each year, but nothing else. It's working fine. What about plugs, transmission, brake fluid, antifreeze, etc.? I am keeping the car, what do you recommend?

A: Your extraordinarily low annual mileage — roughly 2,400 miles per year — certainly extends maintenance intervals, but does not eliminate them. Check your owner's manual. Besides changing oil and filter as you've been doing, my ALLDATA automotive database calls for tire rotation every 5,000 miles, spark plug and air filter replacement at 30,000 miles and a coolant flush at 50,000 miles. There is no call for transmission service. I would recommend either bleeding the brakes to exchange old brake fluid for new, or at least siphoning the master cylinder nearly empty and refilling it with fresh brake fluid every two years.

Motoring note: Thanks to an anonymous reader for this: "I just read the question about how to fix a screechy belt. I had a similar problem and I replaced belts and checked the tension — the usual stuff. My brother suggested that the pulleys might be out of alignment. Sure enough, the mechanic checked and found that one pulley was not in alignment with the others. He made the adjustment and no more screeching."

Paul Brand is the author of "How to Repair Your Car" and "How to Repair Your Truck and SUV," published by Motorbooks.