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Putting a Premium on Choosing the Best Gasoline for the Car


"And don't forget to only use premium gas," yelled the salesman as I backed into a rainy night, steeped in that stomach-roiling, new-car-scented miasma of consumer exhilaration and sudden staggering debt. My husband and I had literally closed the joint, hammering out the final details of our Passat Wagon purchase as sales personnel and mechanics headed home to their families and Sunday dinner. For 20 minutes, we huddled with the salesman and our toddler son in our brand spanking new car, while the former explained the gadgetry and the latter practiced for the Olympic trials in automotive gymnastics.

"Uh-huh, uh-huh," I said as instructions regarding the rear windshield wiper and side window defoggers floated through my brain.

But the bit about the premium gas I caught. Because I never, ever had used premium gas in my life. In fact, I considered premium gas a symbol of capitalism run amok. A few years ago, I had convinced a friend that he was burning money by putting premium gas into his '87 Camry.

Browbeating him with source after source, I explained that the only cars that needed premium, or high-octane, gasoline were really old cars, cars with audible engine knocks and very high-performance European cars. Like Lamborghinis.

So suddenly I'm driving a Lamborghini?

I did what all the "car experts" tell you to do: I checked my owner's manual. Because the Passat has a turbo engine, the folks at VW "recommended" that premium gasoline be used to ensure "optimum performance" and that certainly nothing lower than 87% octane ever be used. For some reason, perhaps because I have a naturally skeptical, probing mind, or perhaps because premium prices had just jumped to $1.75, I remained unconvinced. Why would a modern, computer-chipped engine require high-octane gas?

So I called the VW consumer service line, where someone named Kelly informed me that although VW recommended premium to "increase fuel efficiency and acceleration," one could, if one preferred, use regular gas and do no harm to the engine.

Although this was the answer I was looking for, I did not stop there. I called the local VW dealership and got a fast-talking mechanic on the phone. He attempted to explain the turbo engine to me, filling my already addled brain with an image of a blade and an exhaust system that somehow filters the gasoline twice, giving my four-cylinder engine the speed and spirit of its V6 cousin.

"But you gotta use premium," he said several times, quite emphatically. "Or else you'll burn that engine right up."

An outside source, I felt, was required. So I called Peter Bohr, a contributing editor to Road and Track as well as a columnist for Westways, the Automobile Club's magazine.

The purpose of octane, he explained gently, was to aid an engine's resistance to knock--the sound an engine makes if it is combusting improperly. Very few cars require premium gasoline, he confirmed. Some older cars and persnickety high-performance European models run better on premium. But because most cars today have computerized systems that adjust the timing of the engine, even higher-end models can adjust to lower octane gas.

Not that he would advise flouting the recommendations of the manufacturer. "If your owner's manual recommends premium," he said, "then you are going to get the optimum acceleration and gas mileage by using it. ... Otherwise, it is simply a waste of money."

Being right is always a solace. Whether it's worth $1.75 a gallon, I haven't decided yet.


Mary McNamara can be reached at

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