Volkswagen Passat TDI Diesel
Save the performance wails: It gets 37 mpg in town, 45 in the woods.
By DON SCHROEDER

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In terms of getting its new cars to the American market on schedule, Volkswagen's recent performance has been running right up there with Mr. Tortoise's quarter-mile times. The 1993 introductions of the U.S. Jetta and Golf models, for example, were tied up for months due to airbag supply problems and strikes at the assembly plant in Puebla, Mexico. Even the turbo-diesel Passat you're looking at here, with the engine that has been setting sales records in Europe for a year now, was due on these shores more than a year ago.      We can understand VW's no-hurry stance regarding diesels in North America. The last oil burner it offered, the "ECOdiesel" Jetta of circa 1991-93, accounted for just seven percent of the Jetta's total sales during that time frame. That's a far cry from 1981, when diesels accounted for 52 percent of all Volkswagen sales in this country. Back then, diesel fuel cost about 20 percent less than gas. Now, diesel runs about 10 percent more than self-serve, unleaded gas. That may explain why in the Eighties there were more than a dozen automakers offering diesels, while today there are just two that still produce diesel cars: Mercedes-Benz (which just dropped the S-class diesel option in the U.S., offering only an E-class diesel here)(MB stopped importing diesels after 1999 - Scott) and Volkswagen.

Diesels are considerably different from gasoline engines. A gas engine first mixes the fuel and air, then compresses the mixture, and finally ignites it with a spark. With a diesel, fuel is injected directly into the cylinder near the top of the compression stroke, where it is immediately ignited by the heat of high compression (diesel compression ratios are often 17:1 or higher). The combustion chambers in most passenger-car diesel engines include a small prechamber into which the fuel is injected. Ignition begins in this chamber, then propagates into the cylinder. That prechamber promotes more reliable ignition and soaks up knocking noise, but it also absorbs heat that would otherwise be converted to power.      VW's innovative TDI, or Turbo Direct Injection, does away with the prechamber and injects the fuel directly into the cylinder. This is also the first passenger diesel to have completely electronic fuel distribution from accelerator pedal to injector. The precision of this system combined with a swirl-inducing intake port and a carefully shaped piston well allowed engineers to achieve reliable ignition without the power-robbing prechamber. With the help of a turbocharger and an intercooler, the 1.9-liter four-cylinder TDI engine develops 90 horsepower and 149 pound-feet of torque, considerably more than the old 1.6-liter ECOdiesel's 59 horsepower and 71 pound-feet of torque. As in the ECOdiesel, a catalytic converter--a three-way in the TDI--is employed to reduce emissions, allowing this diesel to pass California's strict emissions hurdles. VW proudly calls attention to this technology by stamping "TDI" in chrome on the Passat's rump and in big letters on the engine's plastic cover.

Clive Warrilow, president and CEO of VW of America, insists that "the TDI is the diesel that doesn't know it's a diesel." If that's true, this engine has to get out of the garage more often. The TDI wears the diesel badge with conviction, from its glow plugs (which now require only 5 to 10 seconds to preheat the combustion chamber before starting, even on frigid days) to its chattering idle, which sounds louder outside the car than the prechamber-equipped ECOdiesel Jetta's we tested. There is also smelly smoke after a cold start, but only briefly.      The TDI's power is remarkable for a diesel. It motivated our Passat to 60 mph in 11 seconds flat, a substantial improvement over the 16.2 seconds the Jetta ECOdiesel required, and the Jetta weighed 523 pounds less. That's also only 1.7 seconds behind the last gasoline-fed four-cylinder Passat we tested. There are some who will arch their eyebrows at Warrilow's declaration that the TDI is "fun to drive," particularly those who notice that its engine runs out of breath 300 rpm earlier than its advertised 4700-rpm redline. Eighty-mph cruising is a piece of cake for this engine, though, and its prodigious torque is obvious. Drop the clutch at 3000 rpm, and the Passat TDI will leave two 10-foot-long stripes of Goodyear Eagle GA compound on the pavement. Warrilow might consider proclaiming the TDI "the first diesel to burn rubber."

     There's no quibbling over fuel economy. The manual Passat TDI's 37-mpg EPA city mileage beats the Passat 2.0-liter four-cylinder's 21-mpg city by a whopping 76 percent. Highway mileage, at 45 mpg, is a 55-percent improvement. With an 18.5-gallon fuel tank, the Passat TDI has a range of more than 800 miles. Figuring in the current price premium paid for diesel, an owner who drives 15,000 miles a year at the EPA's city rating of 37 mpg would take about three years to recoup the $940 option price of the engine. After that, in the words of one Midwest grocery-store ad jingle, "It's Farmer Jack savings time!" Maintenance intervals and costs are comparable to a gas Passat's.

The flat-black instrument panel is looking elderly even by conservative German standards, but the rest of the cabin is done up in eye-soothing cloth upholstery, neatly tufted on the doors.      The rear seats split-fold forward, expanding the already impressive 14 cubic feet of trunk space, and the firm front buckets come with height and lumbar adjustments. The adjustable steering wheel is more horizontal and distant than most. With the diesel's distant droning, Greyhound-bus drivers might find this oil-burner Volkswagen oddly familiar.

     This car is all about efficiency. For a bare minimum of diesel hassles and a thousand or so bucks, you get the interior room of a Toyota Camry combined with the fuel economy of a Ford Aspire. VW intends to pitch the engine to the green-minded, reminding them that the TDI emits 20 percent less carbon dioxide than a similarly sized gas engine, and that diesel fuel takes less energy to refine. The company hopes that's good enough to sell 14,000 TDIs in 1996 Golfs, Jettas, and Passats--about the number of Passats sold in 1995. When bottled wheat-grass extract and organically grown spirulina turn up at the local truck stop, you'll know that Volkswagen is succeeding.

     The TDI will soon be made available across the model line of VWs sold here, but the engine arrives first in the Passat sedan and wagon, with a manual or an automatic transmission. Although the Passat has made strides since its unremarkable long-term stay with us in 1991 (C/D, July 1992), it nonetheless retains its European quirks and charms. The handling is nicely balanced, with good roll control, accurate steering, and a somewhat firm ride. The door locks can still be exasperating--they don't easily accept the key--and the central-locking system operates as slowly as molasses.

Highs: Long-term-dividend economy, sure-footed suspension, and cavernous interior; New York to Chicago on one tank.

Lows: Searching for diesel pumps, Peterbilt soundtrack, party-pooper engine redline.

The Verdict: The Holy Grail for penny pinchers and Earth Firsters.

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