I have been a fan of diesel powered Volkswagens ever since my cousin owned one in the 1980s. Yes, it was horrendously slow, taking 20-odd seconds to accelerate from zero to 60 miles an hour. But it also got about 60 miles per gallon and was more nicely made than typical economy cars of the era.

Today’s diesel cars, from Volkswagen and other car makers are no longer slow and don’t sound or smell as bad as they used to. And their fuel economy is impressive. VW Jetta SportWagen I am test-driving easily logs 30 miles per gallon around town — a figure similar gasoline-powered cars struggle to approach even in steady highway driving.

But if I was in the market for a diesel Jetta, I’d stick with the manual-transmission model and avoid the automatic.

Or should I say, “automated manual” or “dual-clutch transmission?” The Jetta diesel has what Volkswagen calls a DSG. It is essentially the same thing that Porsche calls a PDK, BMW calls an SMG and Maserati calls (or used to call) a Cambiocorsa.

It’s another name for a transmission that has a clutch mechanism like that of a traditional stick-shift. But there’s no clutch pedal. The car automatically does the clutching for you. And that’s where the problems start.

I feel like I could do a smoother job of clutching than the robotic system, especially at low speeds or while maneuvering in parking lots. With the diesel engine the problem is worse. Compared with a gasoline engine, the diesel generates more pulling power just as the car starts moving. The result is often a lurch or a lunge as the automated shift mechanism “drops the clutch.”

It seemed like the clutch engaged a bit too late to get a smooth launch and too abruptly at other times during my drives. Even while cruising at speeds between 30 and 40 mph the car would waver, its speed increasing and decreasing even though the accelerator pedal was steady.

Dual-clutch transmissions are gaining popularity, especially among enthusiasts who see them as racing technology. After all, Ferrari developed the concept for its Formula One racers two decades ago and later adapted it to road cars. But what works on the track or in high-performance sports cars might not be ideal for the family wagon.

Longtime diesel fans may opt for the traditional manual transmission on the Jetta because it has a higher fuel-economy rating of 30 mpg in city driving and 42 mpg on the highway, compared with 29/39 for the DSG. Others may avoid the DSG because they don’t like listening to passengers complain about the jerky ride.
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