The Pressure’s On

by Volkswagen; Mercedes-Benz Volkswagen Touareg V10 TDI; Mercedes E320 CDI Volkswagen; Mercedes-Benz

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In the 1970s, Americans had a love/hate relationship with diesel cars. Though more fuel-efficient than their gas cousins, the cars were noisy, underpowered, smog-belching reminders of just how badly the fuel crisis had crippled the nation. By the mid-’90s, lower gas prices all but banished them from U.S. showrooms.


Meanwhile European carmakers, spurred by diesel-friendly tax structures, kept at it. They traded sloppy mechanical fuel injection for high-pressure electronic systems that better atomize fuel.


Finer droplets burn more completely than a coarse spray, cutting noise and emissions while boosting power. The result: a new generation of surprisingly appealing diesel vehicles.


The first two arriving in the U.S. use opposite approaches, but both are well-performing alternatives to gas cars.


Volkswagon Touareg V10 TDI
Specs: $57,800; 23 mpg highway/17 mpg city


Volkswagen’s cleaner diesel uses a Bosch system called Pumpe Dse (“unit injectors”), which pressurizes the fuel to 29,733 psi at each cylinder. The engine is a twin-turbocharged, 310hp V10 that, VW says, goes from 0 to 60 in 7.5 seconds (it has 553 pound-feet of torque).


A plasma coating on the cylinder walls protects the engine from the rough wear inherent in diesel combustion. The final product is one of the most powerful SUVs on the road.


Mercedes E320 CDI
Specs: $49,800; 37 mpg highway/27 mpg city


Mercedes approaches the diesel dilemma with common-rail injection, a technology, also developed by Bosch, that uses a fuel-line loop supplying constant, highly pressurized (23,000psi) fuel to solenoid injector valves in each of the turbocharged engine’s six cylinders. The E320 cranks out 201 hp, 369 pound-feet of torque, and reportedly races from 0 to 60 in 6.8 seconds. Although there’s some noise in the engine at idle—like a Cuisinart crushing ice cubes—you can hardly tell you’re in a diesel, especially when you’re dusting trucks on the highway.