The US Debut of the Smart ForTwo at Herb Chambers Companies Somerville !

The tiny Smart car, fighting sluggish US sales, is getting a jolt under the seats.

That is where the lithium-ion battery pack sits in the new electric version of the two-seater, located where its 8.7-gallon gas tank used to be.

The Smart ForTwo Electric Drive made its local debut yesterday at the Herb Chambers dealership in Somerville. Taking a cue from BMW, which leased its prototype electric Mini Cooper last year to 500 American drivers, Smart is bringing 250 test models of its electric car to the United States. They will be available through special lease programs, but most will be sold to corporate fleets.

Smart plans to build 1,500 before official production begins in 2012. The four-year lease is expected to cost $31,500, about $10,000 more than the most expensive gasoline-powered Smart, according to Derek Kaufman, one of the brand’s vice presidents.

“What we’re really trying to promote here is the electrification of transportation,’’ he said.

The Smart car, made by Daimler AG, was introduced in Europe in 1998, and brought to the US market two years ago, when gas prices hovered around $4. Nearly 25,000 of the tiny two-seaters were sold that year.

Now that fuel prices have ebbed, Smart has struggled to market a microcar with scant luggage space and average fuel economy. Smart’s US sales through June are down 61 percent over last year, with only 577 sold last month. Herb Chambers, who owns two Smart dealerships, says that in a “good month,’’ he sells up to 20 of the cars.

“If fuel were $4 a gallon, there wouldn’t be a car sitting here,’’ Chambers said in his Somerville showroom.

Other than green wheels, decals, and two circular gauges atop the dashboard to show battery life and available power, there’s no apparent difference from the regular Smart. Power cables stow inside the tailgate, and the motor and other electrical components hide under the cargo floor.

Despite adding roughly 300 pounds worth of batteries engineered by California-based Tesla Motors, the 8-foot, 10-inch ForTwo barely weighs a ton. Maximum speed tops out at 60 miles per hour and its range is 84 miles. A complete charge from a standard outlet takes about eight hours.

Later this year, a wave of electric cars is expected to go on sale.

Buyers of electric cars can qualify for up to $7,500 in federal tax credits.

Clifford Atiyeh can be reached at catiyeh@globe.com.