Q. I saw an article in the projoCars section about a truck that ran on wood chips. Back in 1945, I drove a truck that ran on wood. I remember starting the truck on gas, and then pulling a knob on the dash to have it run on wood. I believe the city was Steyr, Austria, and the technology was there 65 years ago. So what happened?

A. The technology is known as gasification. It is a process that converts many carbon products (wood, coal, garbage) into wood-gas (hydrogen). It is this hydrogen gas that can run the engine. I believe this was done in the 1940s, when gas was in short supply. Currently, this type of system is being used in some municipal power generation. I can’t say for certain, but with today’s emissions restrictions, building a car that runs on wood chips is possible, although not very practical.

Costly evaporator

Q. I have a 1999 Buick Century and the air conditioning has stopped working. I have been told the car will need an evaporator. I was told the repair was going to cost $1,000 to $1,200 to get the part replaced. This seems outrageous. Will it really cost that much to get my car repaired?

A. If in fact the air conditioner evaporator needs replacing, the part is $280 and it will take about eight hours to complete the repair. Add to this the additional cost to recharge the system and $1,000 to $1,200 is certainly a realistic figure.

Smelly Marquis

Q. I own a 1997 Mercury Marquis. For the past nine months I have been experiencing gas fumes in the car when my window is down. I brought the car to a Ford dealer and they did a smoke test to see if there were any fumes escaping and checked for a gas leak, both were negative. I also had the spark plugs changed, the plug wires and coil packs replaced. The repairs reduced the fumes for a while but now they are back. Could there be something else causing this, like a sensor or electrical? This car is in great shape and has never caused any problems, it also runs like new.

A. Since the repairs seems to minimize the problem it is worth looking at the general running condition of the vehicle. If the vehicle is running lean or rich the exhaust could emit an acrid smell. This will be especially noticeable if the tail pipe does not fully extend past the bumper of the car. Although I still wouldn’t rule out a gas leak. I have seen many Marquis and Crown Victoria models that the gas tank rusts out at the top of the tank. When this happens, you will get a gas smell only when the tank is close to full.

VW Clean Diesel

Q. Do you have any info on the new VW Clean Diesel? I’m already committed to buying the Jetta, but also looked at the Civic hybrid and the Prius. My job requires a lot of driving between Rhode Island and southern New Hampshire. I have already placed an order to buy one and was hoping I made the right decision.

A. The Jetta diesel promises to be a very fuel efficient vehicle and should suit your driving style. Where the Jetta shines is out on the highway where, according to Volkswagen, you should be able to see 50 miles per gallon. Hybrids, on the other hand, generally get better fuel economy when driven in the city when the electric motor does most of the work.

Colorful antifreeze

Q. I have a 1994 Toyota Camry and was considering changing the antifreeze. To my surprise the antifreeze was red, not green type that I’m use to. The second issue is according to the vehicle owner’s manual there doesn’t seem to be a recommendation to change it. Should I at least drain it and refill it?

A. There was a time when antifreeze was only green and you changed it every two years. Today, there are at least six different formulations of engine coolant, some of which are good for five years. Your Toyota uses a long-life antifreeze that has a claimed 100,000 mile life. That doesn’t mean it shouldn’t be checked for both freeze protection and contamination. This is something you should check at each oil change.