Surprisingly, the 2009 Jetta TDI is the only diesel-powered car priced under $40,000 available in Canada right now. (The diesel Smart Fortwo was replaced in 2008 with a gasoline version). In other parts of the world, diesel cars often make up 50% or more of the total passenger car market, and have done so for a long time.
Let’s cut to the chase: official Energuide fuel economy figures for the 2009 Jetta TDI sedan are 6.8/4.8 L/100 km city/hwy (manual transmission) and 6.8/4.9 L/100 km city/hwy (DSG automatic). My test car had the optional DSG transmission, and over a week of careful driving using fuel-efficient driving techniques, I managed 5.7 L/100 km (50 mpg Imperial) which is almost exactly Energuide’s combined rating.
Apart from the driver’s skill, two key features of the Jetta TDI make it possible to attain this excellent fuel economy: the turbocharged engine’s generous torque at low revs, and the six-speed DSG automatic transmission. The diesel engine’s healthy torque enables the Jetta TDI to cruise along and even accelerate up hills without the engine going over 2,000 r.p.m., and when driven gently, the transmission will shift up before 2,000 r.p.m. Similarly, cruising on the freeway, the engine revs at just 2,000 r.p.m. at 100 km/h in sixth gear. The lower the engine revs, the less fuel it uses.
Source: Canadian Driver