GM has made the bold claim that hybrid versions of the Chevrolet Tahoe and GMC Yukon SUVs will achieve 40% better fuel economy than regular petrol versions, equating to a mileage figure of roughly 19-20mpg in urban driving. Earlier forecasts predicted improvements of only 25%, but, according to USA Today, pre-production versions have proven more fuel efficient than some family sedans as well as new crossover vehicles that are stealing sales from traditional truck-based SUVs.

The first batch of hybrid models will actually cause GM to lose money, said an official. The hybrid hardware adds on average $10,000 to the cost of the SUV, however, GM is yet to finalize pricing for the new models, which will go on sale this autumn.

Both trucks are powered by GM’s new dual-mode hybrid that was co-developed with DaimlerChrysler and BMW and should start appearing in Cadillac models next year. Despite the new hybrid drivetrain, the SUVs will still be able to tow up to 6,200 pounds and maintain a conventional 4WD system with low-range gearing.