Q. Is the Rolls-Royce considered the most luxurious car in America? -- B.W., Chicago

A. Some may think so. But, for the fourth year in a row, "America's most affluent consumers" have named Porsche the most prestigious car available, according to the Luxury Institute's 2008 Luxury Brand Status Index survey. Lexus and Mercedes-Benz ranked second and third, respectively. The institute said it conducted an online survey of more than 1,600 American consumers with an average income of $349,000 and an average net worth of $3.7 million. "Our surveys inform luxury CEOs on the health of their brands in no uncertain terms so they can take action to enhance relationships with prospects and customers," said the independent ratings and research institute. "Customer perception is everything in the luxury market," Porsche Cars North America said in regard to the survey's results.

Q. What do you think of Mercedes-Benz television commercials for that automaker's new Mercedes high performance C63 AMG sedans that are shown "smoking rubber" and "burning tires" on a track? --E.M., Chicago

A. The commercial makes Mercedes look as if it expects the car to be bought by reckless drivers with 10-year-old mentalities. I tested the $53,800 Mercedes C63 AMG on desert roads near Phoenix (March 10 AutoTimes) during a media preview of the car and saw no outlandish driving behavior, although the event was attended by several auto magazine writers who often drive aggressively.

Q. I saw a new high-performance Ford Mustang that had a license plate that read "525 HP." Is the car's owner exaggerating or does that Mustang really have 525 horsepower? --J.R., Chicago

A. The 2008 Shelby GT500KR (King of the Road) Mustang, engineered by Ford Motor's Special Vehicles Team (SVT), with input from legendary racer/car builder Carroll Shelby, has the highest Mustang factory rating -- at 540 horsepower, SVT spokesman Patrick Hespen said. The Shelby Mustang GT500 has the next highest rating, at 500 horsepower. But maybe the car's owner modified his GT500 with aftermarket parts to get 525 horsepower-- or couldn't get a license plate with the correct factory horsepower rating.

Q. I'm in the process of buying a new car and plan to give my current auto to my mother, who lives in Indiana, about 80 miles from Chicago. Her car is older than my father's car, which we sold after he passed away, so another auto would be a comfort for her to drive. But how do I get my car to her without license plates? I want to keep my current plates for my new car because they are vanity plates. --M.L., Chicago

A. You just need a $10 seven-day drive-away permit, which is available at any Illinois secretary of state facility. But you must take your title and identification with you. Then you can drive your car to Indiana, where your mother must register it and put Indiana plates on it, says Elizabeth Kaufman, a spokeswoman for the Illinois secretary of state's office.

Q. I was thinking about replacing my 1971 Cadillac's radiator, which I bought new. The car has been driven 72,523 miles, but my mechanic says the radiator is OK. Also, how often should I have the radiator filled with new antifreeze? --P.B. Chicago

A. The radiator seems OK, so I don't advise replacing it. You should change antifreeze once a year because it has rust-preventing additives that break down.

Q. I'm buying a 2001 or 2002 Lincoln Navigator SUV driven 110,00 "highway miles" before relocating to Ghana in West Africa, a tropical rain forest region. I want to substitute 18-inch wheels for the 17-inchers this Lincoln originally came with. I don't know if an all-season tire or off-road all-terrain tire will work best. Also, should I replace the suspension? --H.O., Chicago area

A. Opt for a 285/60, R18 (18-inch) tire-wheel combination, using off-road all-terrain tires, advises the Tire Rack, which is the country's largest independent tire tester (1-888-374-8473). Give the suspension heavier duty shock absorbers.

Q. What's the best commuter car? --E.B., Evanston

A. One might guess it would be a hybrid auto, but it's the 2008 Cadillac CTS, says NewCarTestDrive.com and CarsDirect.com Web sites, which have personnel that evaluated major current models in tough commuter traffic. Their list features 10 vehicles from the 2008 model year that "best meet the needs of commuters across the United States." Besides the CTS, the list includes the Toyota Yaris, Honda Fit, Ford Focus, Toyota Prius, Chevrolet Malibu, Toyota Camry Hybrid, Saturn Vue Green Line hybrid, Buick Enclave and Acura RL. Cars were chosen that have overall refinement, excellent driver visibility, controls that work without distraction, comfortable seats and secure cupholders -- besides safety features including side curtain air bags and electronic stability control.

Car question? Send it to Dan Jedlicka, Chicago Sun-Times, 350 N. Orleans, Chicago, IL 60654, or e-mail djedlicka@suntimes.com. Include name and hometown, and be sure to include a self-addressed stamped envelope to ensure a personal reply.