Updated

The impact of new gas-mileage rules on passenger cars gets all the attention, but proposed increases apply to commercial vehicles too.

That means that automakers will be redesigning their commercial vans for better fuel efficiency too.

In 2013, Ford will start building its full-size Transit van in Kansas City, replacing the current Ford E-Series, the best-selling full-sized van for 32 years now--which is probably still better known by the Econoline model name that Ford hasn't used since 2001.

Vote: Favorite Full-Size Van

Today's E-Series dates all the way back to 1992, with its last major update (which lengthened the front end) in the 2008 model year. Even Ford calls it "venerable" in its press materials, an admission that it now has the oldest doors in the business.

The new Transit van will also replace the current European van with the Transit name, on sale since 2006 and dating back to the 2000 model year.

Slideshow: End of the Line for the Ford Crown Vic

Under Ford's globalization plan, a common global platform design will be adapted for all markets--the largest being Europe, North America, and China--offering cargo, passenger, and chassis-cab variations.

Ford has released few details of the new vehicle thus far, but it says the Transit van sold here will get gas mileage ratings at least 25 percent higher than today's E-Series vans--lowering both CO2 emissions and customer running costs as a byproduct.

The current European Transit is offered in a variety of models, with two different turbodiesel engines, a choice of wheelbases and roof heights, and even front-wheel, rear-wheel, or all-wheel drive. Like the smaller and unrelated Transit Connect van, it's built in Turkey (as well as other locations) for sale globally. More than 6 million have been sold.

Read: 2011 Ford Transit Connect Electric

U.S. models will likely offer at least one EcoBoost direct-injected and turbocharged gasoline engine. Whether Ford offers a clean diesel model remains up in the air, though fleet owners are likely to push heavily for at least one such offering.

The Transit van coming in 2013 won't replace the entire E-Series line; heavier-duty chassis-cab versions of the old E-Series will remain in production for most of the current decade.

The light-duty models will transition to the Transit by 2014, however, which will also offer far more modern technology, and better handling. Part of the fuel economy improvement will come from weight reduction; Ford says the new van will be 300 pounds lighter than today's comparable E-Series models.

Read: The Ford Bronco Returns

Ford is building new test roads on its proving grounds north of Detroit, modeled after urban torture tests used in its Belgium development facility, to ensure the unibody Transit van is as durable as the E-Series, which has a separate body and chassis.

Among the tests it must pass: Climbing steep urban street curbs thousands of times.

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