Q. I accidentally put regular unleaded gasoline in my 2006 Acura, which requires premium fuel. It’s the only time I’ve done this and am wondering about the consequences, or if there is anything I should do immediately. My wife isn’t going to be happy, but I’ll handle that on my own. —W.B., Chicago area

A. You did absolutely no damage to the car, and your wife will never know what happened if you don’t tell her. She most likely wouldn’t care if you did tell. Some automakers recommend premium unleaded gasoline for certain models because it provides the best performance. But they say it’s acceptable to use regular-grade unleaded fuel instead of premium if you’re not making an engine work extra hard by, say, towing a boat or trailer (or trying for the fastest acceleration). With higher gas prices, I’ll bet many motorists are filling their vehicles with regular-grade fuel even if premium is recommended. Their engines automatically adjust for the lower-grade fuel. Some motorists never look at their owner’s manual to see what type fuel is needed and have wasted money by buying premium gas, although it won’t give better performance or fuel economy if the engine is set up to use regular-grade fuel — which is all most engines require.

Q. Have you tested the Buick Lucerne, and what do you think of it? —P.K., Chicago area

A. I tested the then-new 2006 Lucerne for the Jan. 16, 2006, AutoTimes and gave it a good review. It shares its basic design with the Cadillac DTS and hasn’t changed much, although a sportier Super model with a 292-horsepower V-8 is added for 2008. However, the carryover 197-horsepower V-6 and 275-horsepower V-8s are fine, with the latter providing better merging and passing. But the Lucerne still has a four-speed automatic transmission. It’s smooth-shifting, but rivals have a more modern five-speed or six-speed automatic.

Q. In the last two months, my 2001 Toyota Solara emits an annoying hum from the front end when I’m driving. The noise stops when the car is standing still, so the sound isn’t coming from the engine and no dashboard warning lights are coming on. —R.G. Buffalo Grove

A. Your car likely has bad wheel bearings, which have been damaged by this winter’s potholes. One way to tell is that the noise will get louder if you turn the steering wheel is one direction and then will become quieter or disappear when you turn it in the other direction, says Frank Caira, of Elmwood Park’s Caira Automotive, who says he’s seen that this winter’s damaged roads “are really tearing up cars.”

Q. My wife and I are retired and live in Belvidere, Ill. We mostly drive around the Rockford area but visit our children in Batavia, Genoa and Battle Creek, Mich. We also take drives of 400-500 miles to a few other states. We’re thinking about buying a Chevrolet HHR. It looks roomy enough and has good fuel economy. —A.S., Belvidere

A. I like the HHR, which is Chevrolet’s answer to the retro-style Chrysler PT Cruiser, with Heritage High Roof (HHR) styling inspired by old Chevy Suburbans. That styling helps give the HHR a roomy interior despite its compact size, which makes it easy to park and maneuver. A new high-performance SS model with a turbocharged 260-horsepower four-cylinder engine is added to the 2008 HHR line, but you’re best off with the mid-range 2.4-liter, 172-horsepower four-cylinder. The base 2.2-liter 149-horsepower “four” provides only marginal performance and doesn’t deliver much better fuel economy than the 2.4, which provides 22 mpg in the city and 28 on highways with either a five-speed manual or four-speed automatic transmission. The PT Cruiser and HHR were designed mainly for young car buyers but have become popular with older folks because of their economy and practicality.

Q. You’ve written that the Dodge Viper is more of a limited-production sports car than its only genuine American rival, the Chevrolet Corvette. How many Vipers have been built? —W.E., Evanston

A. The Viper debuted as a concept car at the 1989 Detroit auto show and arrived as a production model for 1992. Dodge announced that the 25,000th Viper recently rolled off the assembly line. Chevrolet sold 33,685 Corvettes last year.

Q. I own a 2005 Nissan 350Z convertible sports car and wonder if it ever will be a classic. I only drive it about 1,000 miles a year. Is there a similar car I should look at instead of my 350Z because I’d like to own one that some day may be considered a classic. —P.R., Deerfield

A. You have a fast, racy looking sports car that’s also a convertible, which is the type of body style generally most desired by collectors. But, with the exception of a few cars such as the high-volume 1965-66 Ford Mustang, collectors tend to want low-volume cars. And Nissan has built a good number of 350Z coupe and convertible models (about 19,000 last year, alone) since its arrival in 2003. The 350Z has the attributes to become a collector’s item, but I guess in the distant future. The upcoming limited-production Corvette ZR1 stands a better chance of becoming a collector’s car much sooner.

Q. What’s the most popular car color? I’ve read that it long has been white or silver, but that black is making a comeback. I don’t think you can beat black for elegance. —E.A., Aurora

A. CarMax — a large national used car retailer — says black topped the list as the most popular color for vehicle searches conducted on carmax.com in February. It said black was followed, respectively, by white, blue, red and silver — and that other “colors of interest” to online shoppers included gray, green and (very lastly) yellow.

Car question? Send it to Dan Jedlicka, Chicago Sun-Times, 350 N. Orleans, Chicago 60654, or e-mail djedlicka@suntimes.com. Include name and hometown.