By all metrics, diesel engines are back in the United States, and they aren’t going anywhere any time soon. Once regarded by American car-buyers as loud and annoying, today’s diesel-powered passenger cars are selling well thanks to big torque and far superior fuel efficiency numbers. It’s only natural that these oil-burners would find their way into the best luxury sedans on the market, and the science of building the best diesel is currently the hottest thing in the luxury car world. Of those choices, we’ve picked the top five, all of which stack up well against their gas-powered counterparts with great fuel efficiency and luxury to match.
In many regards, Audi was successful in unseating BMW’s 5-Series as the best “personal executive” (midsize luxury) car that money can buy with the introduction of the new A6 last year. The torquey TDI model further evolves on the formula, a truly remarkable engine with 24 city and 38 highway mpg, not to mention 240 horsepower and 428 welcome lb-ft. of torque. Strapped to standard Quattro AWD, the A6 is nearly as fun as BMW’s offering in the twisties, and sports an overall feeling of even higher quality both inside and out, led by a stunning exterior design, charming interior and fully featured in-car tech.
EPA-rated fuel economy: Up to 24 city/38 highway.
Like with the bmw, BMW’s diesel variant on its award-winning 5-Series is an all-new choice for the 2014 model year. The facts: you’ll find 255 horsepower and 413 lb-ft. of torque, mated to rear-wheel drive and a new 8-speed automatic transmission with manual shift mode, plus 26 city and 38 highway mpg. Choosing between the 535d and 5-Series ultimately comes down to a matter of taste. The BMW is the “purer” driving experience of the two, perfectly sprung and ready for anything, while the bmw is more sure-footed. BMW wins points for its iDrive system, which has finally become intuitive and easy to use while driving.
EPA-rated fuel economy: Up to 26 city/38 highway.
Why did BMW choose to go four-cylinder for its newest-generation diesel 3-Series when the outgoing model came with a six-pot? Fuel efficiency, plain and simple. Fortunately, while earning truly great luxury car numbers of 28 city and 40 highway mpg, the new 2.0-liter turbodiesel is not short on power, with a healthy 180 horsepower and 280 lb-ft. of torque. Zero to 60 mph still comes in just 7.1 seconds, and the 3-Series is still the most fun you’ll have in any entry-level luxury car, diesel-burning or not. The newest-gen car just further refines a formula BMW has perfected over 30-plus years.
EPA-rated fuel economy: Up to 31 city/44 highway.
Mercedes-Benz can rightfully boast that its new 2.1-liter twin-turbo diesel found in the E250 BlueTec is the most powerful diesel four-cylinder production engine in the world, in this application with 195 horsepower and 369 lb-ft. of torque. In the big, broad-shouldered E-Class, of which you can also buy a 500-plus horsepower variant, this may seem like a mis-pairing, but the four-banger proves plenty of power for everyday motoring, and may be all the engine most luxury car owners who aren’t concerned with 0-60 times really want. The 24 city and 38 highway mpg don’t hurt, either.
EPA-rated fuel economy: Up to 28 city/44 highway.
Think of the new Audi A7 as an A6 in a sexy evening dress, its practical five-door hatchback design hidden beneath some truly sensuous curves. While you’ll trade a little in the way of rear headroom, the car is so unique and practical that critics have fallen in love. The diesel engine in question is the same great 3.0-liter turbodiesel as you’ll find in the A6, here matching that car’s 24 city and 38 highway mpg. If you’d like your diesel with a design that dares to be different, the A7 also comes with Audi’s reputation for rock-solid build quality and a fully featured MMI+ infotainment system with Google apps.
EPA-rated fuel economy: Up to 21 city/33 highway.