The VW Jetta is now offered in a semi-astounding variety of drivetrains--combinations of gas engines, hybrid components, or diesel powerplants, and an array of transmission--each with its own fuel economy ratings, from subpar to equally astounding.
The Jetta least likely to win any gas-mileage derbys is the base 2.0-liter four-cylinder. When it's equipped with the standard five-speed manual, it's rated at 28 miles per gallon combined--a figure that's only competitive with mid-size family sedans. With the automatic, it's 27 mpg combined. A better choice is VW's new turbocharged four-cylinder; it's rated as high as 30 mpg combined with the manual transmission, or up to 36 mpg highway, a figure that's still a bit off the pace set by the latest Focus/Elantra/Cruze crowd.
The Jetta TDI diesel sedans are in a class of their own, at a combined rating of 34 mpg (30 mpg city, 42 mpg highway) with either the six-speed manual or the DSG automatic gearbox. Moreover, Jetta TDI owners almost uniformly report that in real-world use, they exceed the EPA ratings for their diesel cars, so fuel efficiency into the high 30s may be obtainable--especially on long-distance high-speed road trips, where diesels excel.
There's also the turbocharged 2.0-liter four found in the Jetta GLI, which delivers 26 mpg combined with its standard manual gearbox, or 25 mpg with a dual-clutch automatic.
The Jetta Hybrid is the most fuel-conscious model, and though it's rare, it's something the hypermilers are seeking out. Its hybrid powertrain (new for 2013) is based around a small 1.4-liter four-cylinder engine paired to an electric motor and the dual-clutch transmission. It's rated at a sky-high 45 mpg combined, just 10 percent lower than the much less entertaining Toyota Prius. That number is more difficult to extract than the TDI's ratings, we've found.
Finally, there's the Jetta SportWagon, built in Germany on the last-generation Golf platform. It soldiers on for one more year in the lineup, with either VW's turbodiesel or its outdated five-cylinder engine. It's rated at up to 34 mpg combined for the TDI edition, only 26 mpg for the gas-powered five-cylinder.