Cold Car Facts: Shifting Perceptions

Cold Car Facts: Shifting Perceptions

COLD CAR FACTS: Shifting Perceptions
A lot of what you think you know about cars is wrong — and mostly, that’s a good thing
By Michael Frank

car_bmwMy father taught me plenty about cars, some of his no-nonsense advice has proved invaluable over the years, like how to dislodge a stuck jalopy from a snow-filled ditch by rocking it with the transmission, quickly shifting back and forth between first gear and reverse. But my father — and a good many other people —put stock in some automotive folk wisdom that either was never true or has been rendered obsolete by new technology. In other words, some of what you think you know about cars — even about hybrids —may be wrong (or right for the wrong reasons). So here with, with all due respect to dear old Dad, I offer a little myth busting.

You have to let your car’s engine warm up on a cold day. False. Unless your car is a bona fide antique, it almost certainly does not need to be warmed up before driving, even in subzero weather. Computerized engine-management systems in cars built since the 1980s monitor a range of factors — including the mercury level outside — and adjust factors like fuel delivery to bring the engine up to optimal temperature during the first five to 10 minutes on the road. In fact, making a cold engine do a little work by burning off the fuel it’s given is a good thing.  Gasoline doesn’t atomize as readily in a cold engine, and extended idling can cause engine oil to mix with unburned fuel in the cylinders, which dilutes the oil, encouraging premature engine wear. It also wastes a lot of gas. So if you think you’re doing your new Range Rover a favor by letting it idle in the driveway for 15 minutes on cold mornings, think again. Thirty seconds is suffcient to circulate engine oil. If you really love your ride, just turn the key, defrost the windows, and get moving.

A heavy car is a safe car.  As far back as the 1930s, conventional wisdom held that the bigger and heavier a car was, the better it would protect its occupants in an accident. But as anybody who witnessed the carnage of a 1950s-era driver’s ed film will attest, that wasn’t always the case. These days, cars’ improving crash-worthiness is negating the need for monolithic bulk, and tighter government regulations aimed at improving fuel economy are inspiring lighter cars too: The less a car weighs, the less fuel it needs to get moving. Still, even the newest hybrids fight a battle of the bulge, because the electric side of the gasoline-electric equation — including motors, power-management systems, and batteries — adds quite a few pounds. The new Mercedes-Benz S400 Hybrid is the first gasoline-electric vehicle to use a lightweight lithium-ion battery array in place of the nickel-metal hydrid cells most hybrids use. The shoe box-size Li-ion pack drives a small, 20-horsepower electric motor that’s sandwiched between a 275-horsepower V-6 engine and a seven-speed automatic transmission.  Even with this hybrid hardware — the S400 weighs a bit more than Mercedes’  V-8-powered S550 — it returns 26 percent better fuel efficiency with no great sacrifice in performance.  And the S400 sells for$3,650 less than the S550, not including a $1,150 federal tax credit.

car_interiorHybrids are slow. Sometimes, but not always. The all-wheel-drive Lexus RX450h, for instance, reaches 60 mph a tenth of a second faster than a comparable non-hybrid RX350. The new BMW Active Hybrid X6, which packs a twin-turbo V-8 and a pair of electric motors with a combined output of 480 horsepower, will sprint to 60 mph in 5.4 seconds, a scant one-tenth of a second shy of the V-8-powered X6 xDrive 50i, and uses 20 percent less gasoline in the process. Porsche’s Cayenne S Hybrid matches a 333-horsepower, 3.0-liter supercharged V-6 with a 52-horsepower electric motor, which together produce 374 horsepower. Early protoypes were about half a second slower to 60 mph than the V-8-powered Cayenne S, but returned some 25 percent better fuel economy than the base V-6-powered model —and Porsche expects better figures with the production version.

Hybrids can’t handle snow .Depends on the hybrid. When Porsche designed the Cayenne S Hybrid, the goal was to give the model similar all-weather performance as any non-hybrid Cayenne. The Hybrid’s eight-speed automatic transmission routes power to a traditional all wheel-drive system, with wheel slippage monitored and compensated for by a phalanx of computers. The Active Hybrid X6 and RX450 are snow-savvy as well — in fact, Lexus stresses that in some ways the hybrid RX is actually better than the RX350 in snow, thanks to its rear-mounted electric motor, which nudges the front/rear weight distribution from 58/42 percent to a more balanced 56/44 percent.

car_engineThe cold makes hybrids less Earth-friendly.Unfortunately, this one’s true, for a couple of reasons. Batteries are a significant component of any hybrid power train, but when the temperature is low, the chemical reaction that allows a battery to store and deliver electricity works less efficiently. The less stored juice available to poser the electric motor, the more the gasoline-powered part of the hybrid system has to work to make up the difference. And because an engine’s catalytic converter – which cleans up noxious exhaust gases before they exit the tailpipe — only starts to work when it’s between 400 and 600 degrees Fahrenheit, your Super Ultra Low Emissions Vehicle will be a bit less super than usual. The solution? Park your hybrid in the garage. Batteries that start the day above freezing mark hold and deliver power more effectively, and a warmer catalytic converter will get to work sooner– so you and your hybrid can get to the business of saving the world a little more quickly.