Q. I’ve heard that turning off a car’s air conditioning and opening its windows while driving to cool off the interior on hot days will increase fuel economy. Wouldn’t that hurt a car’s aerodynamics and thus decrease its fuel economy? — J.T., Clarendon Hills, Ill.

A. A spokesman for Pep Boys, the national auto aftermarket chain, says switching off air conditioning and opening the windows is “inconsequential to gas mileage.” I have my doubts, although “air” does make the engine work harder and thus use more fuel. I wonder if convertible owners who often drive at highway speeds with the top down notice any fuel economy loss, compared to driving with the top up. 

Q. Why doesn’t the road test section of your web site contain more Chrysler and Dodge vehicles? — J.M., Seattle

A. Despite repeated requests, I rarely get test vehicles from the Chrysler Group’s Central Region Communications department, based in Chicago. From what I observe, it just seems to want rewritten press releases about its media test vehicles, not objective reports. No thanks to that! As of this writing, for instance, I’ve long asked for the relatively new Dodge Dart and the latest Chrysler 300 to test, but to no avail. My last 300 review is years old. That’s just unprofessional public relations on the Chrysler Group’s part, robbing readers of useful information.   

Q. What does the name of the famous product “WD-40” stand for? — K.A, Austin, Texas.

A. It stands for “Water Displacement—40th Formula.” It was successfully created by the tiny Rocket Chemical Co. in 1953. Rocket Chemical was under contract to pioneering aerospace company Convair to develop a chemical that could protect the surface of Atlas rockets from rust and corrosion, says the Old Cars Guide to Auto Restoration magazine. The idea was to develop a chemical that could displace moisture and leave a protective film. Rocket Chemical’s 40th formula did the job and worked so well that its employees began using it around their houses, the magazine says. WD-40 was first introduced to the public in 1958. It displaces moisture, penetrates by loosening metal-to-rust bonds and lubricates and protects metal surfaces from corrosion and rust The WD-40 formula is a trade secret, according to the magazine. 

Q.   Your May 2013 letters column said you wrote to famous author Tom Wolfe, noting that he mentioned several vehicles in his latest book “Back to Blood” that never existed—namely, the “Mitsubishi Green Elf hybrid” and the Chrysler “Annihilator.” You also said you wrote Wolfe that a character in the book drives a “Ferrari 403” and that such a model never was built. Did Wolfe write you back? — J.G., Denver

A. Wolfe promptly wrote back a gracious letter. He said he put in the “Elf” and “Annihilator” vehicles as a joke, but should have left out the “Ferrari 403,” which he wrote “didn’t sound like a joke, just misinformation.” Only Ferrari fans who follow that automaker’s arcane model identification system likely caught the error. Wolfe actually wasn’t too far off the mark because Ferrari did make several “400” models—just not a “403.” Blame the publisher’s proofreader.   

Q. Jaguar long has been known for its beautiful, fast cars, but I hear it’s (gag) coming out with a crossover vehicle. Any truth to that? — E.W., Minneapolis

A. There are rumors that Jaguar will build such a vehicle, if only because the crossover market is likely to continue to be hot. However, we probably wouldn’t see a Jaguar crossover for several years.

Q. My early model Porsche needs a timing belt. Should I have the work done by a Porsche dealer or good independent mechanic familiar with Porsches? — E. C., New Orleans

A. Porsches are rugged, but not cheap to buy and maintain. I suspect that the belt replacement can be done for less cost by a good independent mechanic.

Q. Is there any validity to the 0-60 m.p.h. times of vehicles I often see in reviews, especially car buff magazines? — E.N., Milwaukee
A. Yes—and no. The 0-60 m.p.h. time is a general indication of a vehicle’s acceleration. Much depends on the road surface where that acceleration test is being held, outside temperature, driver skill and how much the person behind the wheel is willing to thrash a vehicle and its tires. Violent acceleration is hell on a vehicle’s mechanical components and tires.

Q. Is Nissan reviving its “Datsun” name? I think it made a huge mistake by changing its Datsun name in America to “Nissan” in the 1980s. It caused all sorts of confusion in this country. — E.B., Chicago

A. Many agree with you. However, Nissan Motor has unveiled the Datsun Go. It’s the first model in a line of low-cost vehicles Nissan plans to develop for emerging markets under its revived Datsun brand. Datsun-branded vehicles will be sold, beginning next year, in India, Indonesia, Russia and South Africa. But not in America

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