Although Volkswagen of America Inc. has sold more than 800,000 diesel vehicles in the U.S. in the past 30 years, this latest '09 Jetta TDI model is by far the most significant.

Not only must this unassuming sedan (and 5-door SportWagen) confront the latest wave of super-efficient conventional and hybrid-electric vehicles, it must convince a skittish consumer base that diesels are an affordable and exciting means of conserving fuel and being a good citizen to the environment.

After a stint in a Jetta TDI sedan on the mountain roads of Southern California, it's plain to see what VWA's on about: Advanced turbodiesels produce considerably more torque, achieve 20% to 40% better fuel economy and emit the same amount or less harmful emissions than other, similar-sized powertrains.

In the real world that means a Jetta TDI and its 236 lb.-ft. (320 Nm) of torque can squirt through traffic much better than a Toyota Prius, get at least 500 miles (805 km) per tank and not gag its driver with a black cloud of soot upon startup.

And the Jetta TDI looks and feels like a normal car. No futuristic blob of wind-tunnel shaping or digital pictorial of how the power is getting to the ground, just a well-equipped bit of German engineering that averages about 40 mpg (5.9 L/100 km) in most driving conditions.

With the diesel engine adding about $2,000 to the sticker, pricing for the sedan and wagon, both of which went on sale in August, start at $21,990 and $23,590, respectively. That modest fare buys a 2.0L, 140-hp clean-diesel 4-cyl., 6-speed manual transmission, 10-speaker stereo, 16-in. wheels, antilock brakes, electronic stability control, “leatherette” seating and the auto maker's generally well-appointed interior layout.

The 6-speed Direct Shift Gearbox dual-clutch automatic adds $1,100, with options such as navigation and 17-in. wheels pushing loaded models near $30,000.

A $1,300 federal income-tax credit erases much of the premium for the engine, however, allowing the vehicle's greater efficiency to pay back the buyer's investment quicker than most HEVs would, even with diesel fuel currently costing at least $0.50 more per gallon than gasoline.

As for the Jetta TDI's social costs (noise, emissions), the advanced, high-pressure direct-fuel injection refines the engine's combustion enough that the average passerby wouldn't think of it as a diesel unless told so.

Combined with a regenerating particulate filter, oxidation catalyst and other smog-scrubbing exhaust tricks that eliminate sulfurous odors and make the car Tier 2 Bin 5-certified for sale in all 50 states, the diesel Jetta is less obnoxious to the senses — and the environment — than a herd of organically fed cows.

Because both the Jetta and the TDI engine are relatively small, urea injection, which limits oxides of nitrogen output in larger diesel engines by squirting small amounts of an ammonia solution into the exhaust stream, is unnecessary.

The U.S. Environmental Protection Agency slaps a 29/40-mpg (8.1/5.9-L/100 km) city/highway rating on the Jetta TDI. However, VWA says the EPA's new testing procedures adopted this year favor hybrids and punish diesels by not representing the average U.S. driver's mostly open-road commute.

To prove the point, the auto maker tapped third-party certifier Automotive Marketing Consultants Inc. to conduct real-world fuel-economy tests. The result: a 38/44-mpg (6.2/5.4-L/100 km) city/highway figure.

Being more lead-foot than experienced mileage miser, our time behind the wheel did support VWA's claim the EPA is low-balling the TDI, as our DSG-equipped sedan easily matched AMCI's real-world numbers while climbing mountain roads, carving canyon switchbacks and navigating the greater Los Angeles area's congested thoroughfares.

And driving it was fun and painless. The chassis and 4-wheel independent suspension feel solid and well-tuned for spirited driving, while the smooth DSG gearbox supplies a satisfying power delivery absent from any HEV's electrified continuously variable transmission.

More than 25,000 fanatical TDI loyalists are in line for the new cars, ensuring U.S. sales will account for up to one-third of '09 Jetta deliveries.

VW Begins U.S. Deliveries of Jetta TDI Sedan and SportWagen

Proponents Gear Up for U.S. Diesel Invasion

Awesome efficiency High fuel prices
Solid German feel Current diesel image
No compromises What took so long?

'09 Volkswagen Jetta TDI

Vehicle type: front-engine, front-wheel-drive, 5-passenger sedan

Engine: 2.0L turbocharged I-4 diesel; iron block/aluminum head

Power (SAE net): 140 hp @ 4,000 rpm

Torque: 236 lb.-ft (320 Nm) @ 1,750-2,500 rpm

Compression ratio: 16.5:1

Transmission: 6-speed manual/6-speed DSG

Wheelbase: 101.5 ins. (258 cm)

Curb weights: 3,230 lbs./3,285 lbs. (1,465 kg/1,490 kg)

Base price: $21,990

Fuel economy: 29/40 mpg (8.1/5.9 L/100 km)

Competition: Honda Civic Hybrid, Toyota Prius