The very first president to ride in a car was William McKinley in 1899, but it was Teddy Roosevelt who, in 1902, became the first to lead a motorcade. The place was Hartford, Connecticut, and the car was a purple-upholstered Columbia Electric Victoria. Neither President spent much time in an automobile, however.

President William Howard Taft had a Baker Electric, and a White Steam car, too. According to automotive historian Michael L. Bromley, early Presidents looked at the automobile with some suspicion as a symbol of conspicuous wealth. By 1909, with mass production of the Model T Ford underway, a case could be made that cars were helpful to the masses. And so Taft was able to lead the way--he owned no less than four cars.

In 1977, President Carter made a splash by hosting a hydrogen-powered Cadillac Seville in his inaugural parade. The Caddy, designed by Roger Billings, could also run on gasoline.

As President-elect, Barack Obama has made a substantial commitment to green cars—he wants to put a million plug-in hybrid cars on American roads by 2015. But will he live out his principles? His personal car, a not particularly fuel-efficient Chrysler 300C, was mysteriously put up for sale on eBay in December, with a starting bid of $100,000. The car was pulled before it attracted any bids, so maybe it’s still in the Presidential motor pool.

But Obama definitely has a new car, made by General Motors. A new Presidential Cadillac limousine goes into service January 20, with the two-mile inaugural parade its first public appearance. Since President Kennedy was shot in Dallas in 1963, Presidential Cadillacs have been not only enclosed, but virtually armor-plated. That might be prudent, but it certainly makes the new and rather hideous limo extremely heavy. Even with a diesel engine, don’t expect it to have good fuel economy.

Bromley says he's unsure why Obama really needs a new limousine, since George W. Bush was furnished with a brand-new 2006 Cadillac DTS-based version. "Cadillac probably wants it to reflect the look of its latest models," he said.

The President mover is assembled from a unique assortment of GM car and SUV parts. Details are kept secret, but there’s probably a GM 2500 truck chassis under the Caddy body. The car incorporates five-inch-thick armor, run-flat tires and an interior sealed against chemical attack. With the advanced communications equipment on board, it’s something of a mobile White House.

If he can get away with it, Obama may spend some leisure time in a Smart Car or a Toyota Prius. But when the new limo and his regular flights on Air Force One are taken into account, the President-elect’s carbon profile is likely to go way up in 2009.