In coming years, every car company will make every vehicle it builds greener--meaning more fuel-efficient--courtesy of increasingly stringent gas mileage and carbon emissions rules around the world.

That applies not only to smaller, simpler cars, but also large, heavy, fast, luxurious, and expensive ones too.

Two days ago, we wrote about the new 2013 Land Rover Range Rover and its all-aluminum structure, which saves fully 700 pounds over the previous model. That requires less fuel to propel it through tony suburbs (and very occasionally up rocky mountain slopes).

Now it's Jaguar's turn. Yesterday, the British maker of luxury sport sedans and sports cars unveiled a slew of new powertrains for their XF mid-size sedan and XJ full-size sedan.

Both those cars were previously offered only with a 5.0-liter V-8 engine and rear-wheel drive. For 2013, both models get a new, standard 340-hp supercharged 3.0-liter V-6.

And, for the XF, there's now an even smaller and more economical option: a turbocharged 2.0-liter four-cylinder producing 240 hp. All engines are now paired with a new eight-speed automatic transmission.

Jaguar estimates that the EPA combined rating for the four-cylinder XF will be 23 mpg, with 19 mpg city and 29 mpg highway.

That compares to the base 2012 XF rating of 19 mpg combined, meaning the new engine delivers a noticeable 21-percent boost in fuel efficiency for the 3,660-pound car.

The new engine has lots of technology packed into it: dual overhead cams, gasoline direct injection, and variable valve timing on both intake and exhaust camshafts.

2013 Jaguar XF

2013 Jaguar XF

The low-inertia turbocharger produces peak torque of 251 lb-ft from a low 2,000 to 4,000 rpm, meaning the engine doesn't need to rev screamingly high to deliver its power.

And if the description seems familiar, it may be because the engine--referred to only in selected Jaguar press materials as "Ford-sourced"--is actually the turbocharged Ford 2.0-liter EcoBoost engine used in more plebian transport like the Ford Explorer crossover utility vehicle.

In the 2013 XF, its 23-mpg rating approaches the 25-mpg combined rating of the Mercedes-Benz S 350 BlueTEC diesel sedan we recently tested (though we got 32 mpg, largely in highway travel).

The big diesel Benz, however, is available with all-wheel drive, while only the XF fitted with the new 3.0-liter V-6 can be ordered with four driven wheels--which brings down its estimated combined rating to 19 mpg.

The base price of the new 2013 Jaguar XF with the four is $46,975 (plus a mandatory $875 delivery fee), making it the least expensive Jaguar since the 2008 demise of the unloved X-Type compact sedan.

It's worth noting that Jaguar will fit the same 2.0-liter turbo four to the XJ, in some markets. Given the larger XJ's aluminum structure, it might deliver equally good mileage ratings in a 4,000-pound full-size luxury sport sedan as well.


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