Not Just Engines, but Transmission will Make a World of Difference

by Benjamin Jones on May 19, 2009


Most of the time these pages are covered with discussion about electric, hybrid, or efficient combustion engine news and opinion. However, there is more to a car than the power source. An under-appreciated, but still very important part of any car is its transmission.

In fact, as far as fuel economy goes, transmissions can either make or break the car. Ever wondered why the Honda Fit or Toyota Yaris gets worse mileage than you would expect? It’s because the transmission has shorter gearing to provide better performance with a smaller engine.

In the above video, GM discusses some of the issues linking the transmission to performance and fuel economy while at the same time highlighting their new 6-speed automatic transmissions. A move to the 6-speed gearbox helps on all accounts because it allows for your gearing to span a greater distance without creating too large of a gap between each individual gear.

In short: on the low end you will get better performance through shorter gearing but on the high end you will get better fuel economy through lower cruising RPM. GM is not the only one doing this, of course, but they do offer a nice explanation of how it works even if they do not go into detail about the associated cost increases.

Source: ABG

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1 Tim May 19, 2009 at 9:20 am

Every car manufacturer that has come out with a ‘high mileage’ version of an existing car has gone to lower (taller) gearing. Its literally a no cost option for them to swap out existing 5th gears for lower gearing and gain a few mpg. Its pretty much a no brainer. The problem is consumers don’t like a ‘sluggish’ 5th gear. They want to be able to rocket away without shifting. Just another example of the lazy American way.

2 dcb May 19, 2009 at 11:15 am

I am an american consumer and I want taller gearing.

3 Rob July 12, 2009 at 6:56 pm

Well Tim, that’s a little dismissive. Anyone wants easier, less work, more convenience with performance IF ALL ELSE IS EQUAL.

If they are told the price for the shorter gearing in terms they understand (e.g., “this will cost you $150/year in extra fuel”) and given an option, many may make a different choice.

Or not. But when people get money, they buy back their time (hire gardeners, maids, get coffee at Starbucks, etc.) and they buy back their effort (powered lawnmowers, cars, weed wackers, etc.). This is not just true in the U.S.

We do drive farther, we have farther to drive. In the distance to San Francisco, I can cross three countries in Europe. Do I think it would be a good idea to make the pain of poor fuel economy (and gasoline usage in general) higher? I absolutely do, raise the taxes by a dollar per gallon, or more. I’m fine with that. But let’s figure out what to do with the money to wean us from fossil fuels.


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