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2011 Mercedes-Benz SLK 350 (Daimler AG/Mercedes-Benz)
2011 Mercedes-Benz SLK 350 (Daimler AG/Mercedes-Benz)

You & Your Car

Should I use cruise control to get the best fuel mileage? Add to ...

My friend and I are having an argument. I say you can get better fuel mileage by careful control of the throttle yourself but he says you’re better off using cruise control. What do you say?

Sorry, but I’m siding with your friend.

Like everything else in a modern automobile – including transmissions – cruise control has made huge advances. In the “old” days, the cruise control unit would wait for speed to drop and then call for the significant throttle openings necessary to regain that lost speed. It was not uncommon to lose several km/h and have the transmission drop a gear. Not very efficient at all.

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But a growing number of vehicles are now using electronic throttle control; there is no solid link, whether by cable or control rods, between the throttle pedal and the injection system.

These electronic systems are not only much quicker to respond to even small changes in speed, they can sense inclines and declines.

At the recent launch of the new Mercedes-Benz SLK350 in the Rockies, it was fun to observe the cruise control system actually use the brakes to keep speed from climbing when descending steep inclines.

These new electronic systems are much more capable of tiny changes in throttle opening and thus improving mileage. The U.S. Environmental Protection Agency even lists cruise control among its fuel-saving tips.

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