Q. My 2004 Toyota Sienna all-wheel-drive minivan needs run-flat tires. After two years, the original tires began making a thumping sound. A tire dealer said they were "cupping" and replaced them with another tire maker's run-flats, which are beginning to make the same sound two years later. Who makes a good top-line, reliable run-flat tire? --B.C., Broomfield

A. Something is causing the tires to wear far too quickly. The first thing to check is proper inflation. See the tire dealer about the tires he installed because they must have a warranty. Regarding brand selection, contact tire experts at the Tire Rack (1-800-981-3782), which is the country's largest independent tire tester.

Q. I'm particularly interested in the Volvo C30. What's your opinion of it and other Volvo models in terms of reliability and durability? My 1993 Volvo 240 will likely soon meet its demise. --M.P., Chicago area

A. The new Volvo C30 (Nov. 10, 2007, AutoTimes) is that automaker's lowest cost model, but it is far from bargain-priced. It should be durable and reliable, although not in the same league as, say, a Toyota Corolla. Other Volvos also are pretty sound. The C30 has long, heavy doors and an occasionally choppy ride, but it is fun to drive. Dump the 240 -- it's really an antique by now.

Q. I own a 1997 Chevrolet Camaro Z28 convertible, 30th Anniversary Edition. It has a 350-cubic-inch V-8 and six-speed manual transmission and is highly optioned. What's it worth? --A.K., Mokena

A. The best thing going for your car is the fact that it's a Z28 convertible. The worst thing-- unless you find a car buff -- is that it has a manual transmission because that will turn off those who just want an easygoing top-down "cruiser" and don't want to bother shifting gears -- and those who never learned how to shift. The anniversary model had a special trim package that mimicked colors available for the classic 1969 Z28. That package means little to those in the car biz, so you best sell the Z28 privately. Your car is valued at $9,500 if in above-average condition and $6,195 if in average shape.

Q. I've heard that Isuzu is closing shop in America next January. Is that correct? I ask because I've been thinking about buying an Isuzu Ascender mid-size SUV, which is a clone of the Chevy Trailblazer and thus can be serviced at Chevy dealerships. I've also heard that, as the Isuzu shutdown deadline approaches, buyers might expect to save thousands of dollars, compared to buying a Trailblazer. --D.O., Chicago

A. Isuzu says it will stop selling "passenger vehicles" in America next Jan. 31. However, an Isuzu spokesman says that most Isuzu dealers sell other makes of vehicles and will continue to service Isuzus "for an indefinite period, or until their warranties run out." You have a good chance of saving money when buying an Ascender as the Isuzu deadline gets closer, but the Trailblazer will have better resale value. You thus will make money on one end, but lose it on the other -- unless you plan to keep the Ascender for a long time. Something else to consider: Sales of mid-size SUVs from nearly all automakers are tanking and thus Chevy likely will offer pretty good closeout deals on Trailblazers.

Q. I'm intimidated by the thought of buying a car at a dealership. How can I avoid being cheated? --E.H., Chicago

A. First, remember you're always in control because you're under no pressure to buy -- and a dealer is under pressure to sell. Research vehicle models and get educated about their features. Determine what are necessities for you, such as heated seats or safety features, and where you're willing to compromise. There are many seductive options, but they can cause a vehicle's price to soar.

Know the value of the vehicle in which you're interested by seeing what other dealers are selling it for (visit the Web or local publications) and visit sites such as cartango.com and nadaguides.com to see a vehicle's fair market value. Bring a friend to keep you focused on the task at hand and help you from becoming emotionally attached to a new vehicle. Nearly everything is negotiable and most dealers will work with you on everything you want to work on, such as price, trade-in and extended warranties. But all bets are off if you want a vehicle in great demand because many dealers won't consider selling it unless you pay full list price -- or a considerable amount above list price.

Q. I ran over lots of potholes during the severe winter we recently experienced and wonder if they might have damaged anything under the car. --E.N., Crystal Lake

A. Have your auto's steering and suspension checked for loose, worn or damaged components often caused by potholes and other winter road irregularities. Also make sure the exhaust system wasn't damaged.