(MONEY Magazine) – Q. We followed your advice and bought a 2004 Acura MDX at a discount. The manual suggests using premium gasoline. Do I really have to pour the high-priced stuff into this car?

A. Not at all. You've pocketed smart savings on a fine SUV, and there's no reason to throw your money away on pricey gas. Luxury-auto makers call for 91-octane premium largely because it makes their cars seem more, well, premium. But blithely pumping the "good stuff" will cost you an extra $100 to $200 a year. What it won't do, according to scientists, engineers and oil companies, is make your car run better, go noticeably faster, last longer or burn less fuel. Nor will running on regular gas damage your engine or void your warranty. Because higher-octane fuel better reduces engine knocking (that pinging sound caused by fuel igniting too quickly in the cylinders), automakers can tune engines to squeeze out a little extra horsepower. But run that same engine on regular, and the power loss is a negligible 2% to 4%. Plus, modern engine computers adjust instantly to maximize efficiency for whatever octane you're using. Most high-performance cars are designed to run smoothly and ping-free on regular if premium isn't available. I'll admit to my own occasional premium binge, a guilty habit that prevents me from sticking a low-octane nozzle into a high-class machine. But as the pump dials spin, I know I'm being suckered like a slots fiend.

Q. After reading your story on electronic stability control, I decided it was a must-have and bought the Cadillac SRX. I understand that the technology has reduced deaths in Europe. What about in the U.S.?

A. Finally, federal regulators and watchdogs are studying electronic stability control (ESC), which senses an impending skid and applies individual brakes to instantly restore control. The life-affirming results confirm what I've argued for years: This is the most critical safety advance since the seat belt. That's because unlike seat belts or air bags, stability control can avert crashes completely, not just mitigate them.

Lone-car crashes account for more than half of all highway deaths, and two-thirds of these accidents involve rollovers. ESC prevents rollovers and encounters with telephone poles by keeping a car on the pavement. The National Highway Transportation Safety Administration (NHTSA) found that ESC reduced fatalities in single-vehicle SUV crashes by 63%. And single-vehicle deaths fell 56% in cars and trucks equipped with ESC, according to the Insurance Institute for Highway Safety. U.S. studies show that it could save up to 7,000 of the 28,000 lives lost in crashes each year—if more car makers and consumers insisted on making it standard.

The latest systems add further rollover sensors that help keep the vehicle right side up and that trigger curtain air bags if it does flip. NHTSA will now consider mandating stability control (standard on most luxury and sports models but still sold in fewer than 10% of new cars and trucks overall) if research continues to prove its effectiveness. With current systems costing manufacturers less than $300 per vehicle, it can't happen soon enough.