Diesel straight-six for Tahoe

The Chevrolet Tahoe is a traditionalist SUV founded with design principles that date back long before “SUV” entered the automotive lexicon. At its essence, it’s a wagon based on a full-size, full-frame pickup, and it’s also a truncated version of the Chevrolet Suburban, which in its present mega-luxury guise, isn’t often pondered in the same notion as “efficiency.” Chevrolet is trying very hard to change that perception, starting with an entirely new chassis for 2021 that now incorporates independent rear suspension. It also explains Chevrolet’s decision to offer a new diesel engine for the Tahoe (as well as the Suburban, and its siblings, the Cadillac Escalade and GMC Yukon XL). The new Duramax turbocharged diesel is a straight-six, the first such diesel layout for General Motors full-size SUVs, and the first diesel offered in any GM full-size SUV since 1999.

A clean-sheet design from the engineers at Duramax – which started out as a collaboration between GM and Isuzu – the new inline turbodiesel displaces 3.0 liters, which translates to 183 cubic inches. In terms of architecture, the engine has an aluminum-alloy block and twincam cylinder head, the sort of tech you’d expected to find in a first-generation BMW 5-series. Introduced with the 2020 Silverado pickup, its other technologies include variable intake runners and a variable-displacement oil pump, plus rail direct injection and oil-jet piston cooling. All are aimed at making this very sizable vehicle considerably more efficient. With an EPA-certified highway rating of 33 MPG, the Tahoe still produces 277 horsepower and 460-lbs.ft. of torque, with most of the grunt coming in between 1,500 and 3,000 RPM. The new GM 10-speed automatic transmission is standard, and the gross towing capacity here is 9,100 pounds.

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