2014 Mazda Mazda6Enlarge Photo
Mazda's 2.2 SkyActiv clean diesel will make its first appearance in the sleek, curvy Mazda6. As with the Chevy Cruze Diesel and Volkswagen's numerous offerings, a highway figure of well over 40 mpg is on the cards (even gasoline models get as much as 38 mpg highway), as is stop-start technology and the option of six-speed manual or automatic transmissions.
Mazda claims its Sky-D low compression units will pass Tier 2 Bin 5 emissions standards and even stricter Euro 6 standards due in 2014, without any after-treatment such as urea injection.
Mercedes' most efficient diesel model, the 2014 E250 Bluetec sedan, achieves 33 mpg combined (28 mpg city, 42 mpg highway). Those figures give it a comfortable advantage over its nearest rival from BMW, the 2014 535d, though the Mercedes' 2.1-liter four-cylinder engine doesn't quite have the punch of the BMW's 'six'--even if 195 horsepower and 369 lb-ft of torque is nothing to sniff at.
The 2.1-liter engine also appears in the GLK crossover, where it attains EPA ratings of 28 mpg combined, 24 mpg city and 33 mpg highway. The other two Mercedes diesels, in the ML-Class and GL-Class, each use a 3.0-liter V-6 diesel. All the Bluetec diesels compare favorably to the gasoline variants - the ML350 Bluetec achieves 15 percent better combined economy than the gasoline ML350, for example.
A diesel? In a Porsche? Surely some mistake?
You'd think so, but no--Porsche really does offer a diesel model, in the shape of its Cayenne SUV. It has done in Europe for several years but now it's changing perceptions on this side of 'the pond' too.
Surprisingly, given Porsche's range of sports cars, the Cayenne Diesel isn't the firm's most frugal offering--that honor falls to 2.7-liter versions of the Boxster and Cayman, and the plug-in Panamera S E-Hybrid. But at 23 mpg combined (20 mpg city, 29 mpg highway) it's comfortably ahead of the 21 mpg Cayenne hybrid or the 18 mpg, V-8 Cayenne S.
2013 Volkswagen Beetle TDI Convertible first driveEnlarge Photo
Volkswagen offers diesel engines in six 2014 models--the Golf TDI, Jetta TDI, Jetta TDI Sportswagon, Beetle TDI, Passat TDI and the Touareg TDI SUV.
Aside from the 23 mpg Touareg, which uses a 3.0-liter V-6 TDI also found in Audis, all use the same 2.0-liter TDI turbodiesel engine. Well, for the time being--when the 2014 Golf makes way for its 2015 counterpart, a new TDI engine joins each car's 2015 range with lower emissions, greater performance and improved economy.
For the time being, the Passat TDI with a six-speed manual gearbox is most efficient--it's rated at 35 mpg combined (31 mpg city, 43 mpg highway) under EPA testing standards. We'd expect the new Golf TDI to beat that on each count. Worth a look, for combining fun and frugality, is the Beetle Convertible TDI--32 mpg combined (28 mpg city, 41 mpg highway) is about as good as you'll get during wind-in-the-hair driving.
Prefer diesel trucks? Read our ultimate guide to diesel pickup trucks from Chevy, Ford, Nissan and RAM.