I should have set aside a day to celebrate its being, the goodness and specialness of it. But it was too easy to take it for granted, to expect that it would always be there fulfilling my will.
It’s gone now. Volkswagen took it back to lend to other automotive journalists, many of whom probably will write about it strictly in terms of nuts and bolts, as if those were the things that mattered most.
The 2010 Volkswagen Jetta TDi sedan is far more than the sum of its parts. It is proof that economy and efficiency need not be in conflict with fun-to-drive. It demonstrates beyond a reasonable doubt that one good drive system to move a car or truck makes more sense than the use of two to do the same thing.
The heart and soul of the Jetta TDi is its turbocharged diesel engine. It is a two-liter four-cylinder device that delivers a maximum of 140 horsepower and 236 foot-pounds of torque. (Engineers prefer the construction “pounds-feet torque.” But theirs is a devotion to technical accuracy that loses meaning in translation to daily language.)
“Horsepower,” an English concept derived from the power exerted by a horse in pulling a load, is a technical measure of an engine’s ability to do the same thing. Thus, the traditional thinking in the automobile industry has favored horsepower — the more, the better.
But power and efficiency are not the same. “Efficiency” speaks to management of effort. Power better managed requires less power, which requires less fuel to do identical work.
In a car or truck, “work” speaks to “torque,” the measure of an engine’s ability to create twisting force around an axis, to turn drive wheels. An engine that requires relatively less power to create the same, or relatively more, torque is a more efficient engine.
A turbocharged engine recirculates exhaust gases to drive an impeller that pulls more fresh air into air-fuel combustion chambers, commonly called cylinders. The ability of cylinders to hold an air-fuel mixture speaks to their “volume,” which is expressed in liters in commonly used metric measurements.
Generally, more air and fuel means a bigger bang. But turbo-charging more efficiently combines air and fuel, thereby creating a better bang — more power without an appreciably increased expenditure of fuel.
Therein resides the genius of the 2010 Volkswagen Jetta TDi sedan. It combines turbocharging technology with ultra-low-sulfur diesel fuel to deliver 30 miles per gallon in the city and 42 on the highway, and to do it with muscle and chutzpah. It proves that not all cars need 200 horsepower or more to be considered worth driving.
I drove a Jetta TDi sedan all over the great state of Virginia, using its highways and byways in perfect harmony with substantially more powerful vehicles. Empirical observation indicates that I made better time than many of them, because I seldom stopped for fuel, which means I often caught up with and passed cars that had zoomed past me on tollbooth-monitored highways.
When necessary, finding ultra-low-sulfur diesel, the fuel required for the Jetta TDi, was easy. The fuel has been widely available in the United States since 2006, when the federal government required 80 percent of the nation’s highway truck fleet to begin using cleaner diesel.
Sulfur resides in crude oil, from which diesel is refined. It is the stuff that manifests itself as thick black smoke when traditional diesel fuels, which have 500 parts of sulfur per million, are burned. Ultra-low-sulfur diesel has been refined so that its sulfur content is 15 parts per million. It can be found at many urban gas pumps, and it’s nearly always available at highway fueling facilities.
Diesel engines are 30 percent more efficient than their gasoline counterparts. But, alas, that competence is not rewarded at the pump. Recent price checks showed diesel fuel selling at an average of $2.96 per gallon in the United States, compared with an average of $2.74 per gallon for gasoline.
Also, diesel technology costs more. The base gasoline version of the Volkswagen Jetta, for example, starts at $17,735. The base version of the diesel-powered Jetta TDi is priced at $22,830.
Brown is a special correspondent.
