The Hummer H1s and H2s weighed more than 6,000 pounds. A new Model X is said to weigh about 5,500 pounds, unladen. Its so-called "gross vehicular weight" would likely be over 6,000 pounds -- and qualify it for the tax break.

The $25,000 windfall, available only to buyers who own businesses and are making the automobile purchase as a business investment, would be in addition to other official incentives. Tesla's Model X, as a non-polluting, zero-emissions, battery-electric vehicle, also qualifies for a $7,500 federal tax deduction and a $2,500 California state rebate.

Tesla is particularly adept at using subsidies to market its cars, noting that the tax credits and state rebates help reduce the cost of ownership. 

The news of the tax break comes as the first Tesla Model Xs are beginning to roll onto California roadways. The company's second in-production vehicle, behind its $100,000 Model S electric four-door sedan, experienced repeated delivery delays. The first units were delivered to purchasers late last month, but the first round of deliveries was limited to only six vehicles.

One went to company CEO Elon Musk.

Those interested in buying a Model X can make deposits through the Palo Alto company's website. But they won't be told how much the car will ultimately cost. Tesla has not yet announced a base price for the vehicle.

Musk has previously said the X would start at about $5,000 more than a comparably equipped Model S sedan, which would put the starting price at about $81,200 before federal and state electric car purchase incentives. The price could run much higher with options, as the average transaction price for a Model S is over $100,000.

A Tesla spokesperson declined to address the tax break question. But Tesla spokeswoman Alexis Georgson told the online auto news organization Autoblog that a deduction "could be taken for up to $25,000 of the purchase price" of a new Model X.

But analysts believe the vehicle price could be considerably higher than the Model S, and that the company may have difficulty fulfilling orders.

Morgan Stanley Research analyst Adam Jonas said he estimates the price will be $25,000 more than the sale price of a Model S — "and easily $10k to $15k higher than we had expected," he wrote.