Q. I have a 2002 Chevy Impala LS with 85,000 miles on it and it has developed a shifting issue.  On warm and hot days and after highway driving if I exit to back roads, the transmission shifts hard up and down, especially at slower speeds. The problem does not exist during the cold winter weather. I have checked the fluid and it is full and in good condition. I had the transmission serviced around 75,000. Any ideas?

A. The transmission in your car, like its engine uses a computer. Just like when diagnosing the engine, the first place to start is with a computer check to look for possible fault codes. During the inspection a pressure test should also be performed. If the pressures are not within the specification it is possible one of the valves in the transmission is starting to bind up. This could also be caused by sediment in the transmission. There are several technical service bulletins concerning shift quality that should be investigated.

Q. I am looking to buy a used car and spend roughly $6,000. What would you say is the best bet for a brand/model that will require limited maintenance?

A. The cars with historically lowest average maintenance costs have been Toyota and Honda. The Camry, Corolla, Accord and Civic can be great cars. That said don’t overlook some of the mid-size domestic cars. The Taurus/Sable and Buick Century and Chevy Malibu can be economical to purchase, get decent mileage and are reasonable to repair. Prior to buying any used car, make sure you have it inspected by a reputable garage. How the car was treated prior to you buying it can make a big difference in your cost of ownership.

Q. I have a 2001 Lexus ES300 and have been told it needs a wheel bearing. Can you give me an idea how much this would cost? I have to admit that I’m a little disappointed that my luxury Lexus needs a wheel bearing.

A. Having a luxury name doesn’t mean that your car will never need repairs. In fact your luxury Lexus uses the same wheel bearing as the Toyota Camry. The wheel bearing is a “pressed fit” type bearing which will require about 2.5 hours labor to install. Depending where the bearing is purchased, the part will cost in the range of $50.00-$70.00.

Q. I have a 2007 Toyota Camry and when it was in to have the brakes replaced the dealer recommended a transmission fluid flush. I didn’t have it done at the time, is this something I should consider?

A. Toyota recommends the transmission fluid is inspected on a periodic basis but does not recommend any interval to change the fluid. Unless the fluid level is low (which would indicate a leak) or the overall condition of the fluid is poor, I would leave well enough alone.