Dayton Daily News

Wheels: With gasoline prices increasing, some readers may be looking into purchasing a vehicle that gets better fuel economy, such as a hybrid. Can you discuss advantages and disadvantage of hybrid vehicles?

Halderman: Hybrid electric vehicles, abbreviated HEV, do get better fuel economy than similar conventional vehicles. However, the advantages are realized mostly during city-type driving. A hybrid electric vehicle uses an electric motor to help power the vehicle. The power for the electric motor is delivered by high-voltage batteries, which are kept charged by the gasoline engine powering a combination motor and generator. Hybrid electric vehicles do not need to be plugged into an electrical outlet like a pure electric vehicle. Some concept vehicles do provide the opportunity to charge the batteries by plugging into an outlet, but these so-called plug-in hybrids are not currently in production.

The disadvantages include a higher price than a compatible vehicle and having to become familiar with how to best drive the vehicle for best fuel economy. In some hybrids, such as the Lexus GS 450h, the trunk space is reduced due to the placement of the batteries.

Wheels: An e-mail from Gary says, "My F-150 is a 1999 with a 4.6 L engine and 117,000 miles on it. I have had it since it had 66,000 miles but I have never changed the spark plugs in it, nor have I changed the oxygen sensors (there are 2) and I can't see where the manual talks about changing the timing belt/chain. I think my truck has a chain rather than a belt (just never looked) so that is why the manual does not say anything about changing it. Am I right? Should I spend the money to change the plugs? They are those platinum tip kind and cost a lot, times 8. So, is it worth changing them and the oxygen sensors? I don't want to spend the money if it is not going to give me any returns in mpg and etc. What do you think?"

Halderman: Your truck engine does use a timing chain rather than a belt and as a result, does not need to be replaced on a regular basis. Oxygen sensors normally last the life of the vehicle unless damaged by another fault, such as a defective fuel injector, excessive oil burning, or other similar fault. The spark plugs are a serviceable item and should be replaced according to the recommendations stated in the owner's manual. Most newer vehicles recommend spark plug replacement every 100,000 miles or sooner. Will new spark plugs improve the fuel economy? I don't think it can hurt and you may see a slight increase even though the engine seems to run OK now.

Notice to readers:

It is now officially summer and time for an oil change if you are following the seasons. I'll remind you again in late September.

James D. Halderman is an ASE-certified master technician, a member of the Society of Automotive Engineers and the author of 12 textbooks. Submit your automotive care questions to Halderman via e-mail at jhalderman2@juno.com, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 1611 S. Main St., Dayton OH 45409.