Volkswagens have long been known for their diesel engines, and for 2004, the Jetta wagons and sedans got a more powerful TDI (turbo direct injection) diesel that still achieved around 50 miles per gallon on the freeway. The 1.9-liter diesel, available in the Jetta GL and GLS sedans and wagons, saw its horsepower upped from 90 to 100, giving the diesel-powered Jettas a bit of an extra kick off the line and a bit more help when passing at highway speeds.

The standard engine in the GL and GLS sedans and wagons was a 115-hp, 2.0-liter gas engine. A five-speed manual transmission was standard across the line, with the exception of the high-end GLI packages, which came with a six-speed manual transmission. A four-speed automatic transmission was optional with the gas-engined Jettas, while a five-speed automatic was optional for Jettas with turbocharged engines.

Standard features for the base Jetta GL package included air conditioning, power windows, power door locks, front and side airbags for the driver and passenger, anti-lock brakes, a tilt/telescoping steering column, an anti-theft alarm system, a keyless entry system, cruise control, and a stereo system with a CD player. Higher-end Jettas added such features as a power sunroof, stability control, a leather-trimmed steering wheel, a power sunroof, and heated front seats.

The Jetta's acceleration, handling, braking, and safety features were cited as positive points by drivers, although some noted that frustrating quality-control issues persisted with the car. The electrical system and automatic transmission were singled out by some drivers as particularly troubling.