Diesel engines make a lot of sense in SUVs, mitigating the gas-guzzling effects of big, heavy bodies, poor aerodynamics and large engines.

The Audi Q7 TDI is a good example of this, and Audi has made further improvements for the 2013 model year car, touting 12 percent better efficiency.

Audi is dropping a new generation of 3.0-liter, V-6 turbodiesel under the hood, now producing 240 horsepower and 406 pounds-feet of torque. It's the same unit you'll find powering the Porsche Cayenne Diesel, set to appear in the U.S. later this year.

As with the Porsche, the engine has been refined to produce lower emissions, with AdBlue injection and selective catalytic reduction.

Those figures aren't bad considering an engine weight saving of 55 pounds. As well as the power gains, the new engine is also cleaner and more fuel-efficient.

The new TDI should allow the Q7 to achieve figures of 19 mpg city and 28 mpg highway--up from 17 city and 25 highway. The highway figure now matches that of the hybrid Lexus RX 450h, helped by an eight-speed automatic transmission.

The 2013 Audi A7 TDI has an MSRP of $52,000 in Premium trim, $58,350 in Premium Plus and $64,550 in top-end Prestige trim. This excludes a $895 destination charge, as well as taxes, title, options and dealer charges.


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