Engineers turned to aerodynamic improvements, more gears and a few minor engine tweaks.
The Volkswagen Jetta has received a significant boost in fuel efficiency for the 2019 model year.
The latest EPA listings show ratings of 40 mpg on the highway, 30 mpg in the city and 34 mpg combined, sharing the same figures for the eight-speed automatic gearbox or six-speed manual.
The redesigned sedan carries the same basic 1.4-liter turbocharged four-cylinder engine as its predecessor. Friction losses are reduced, however, by switching to a thinner oil and adding a more efficient alternator and air conditioning compressor.
Engineers also further refined the Jetta's already decent aerodynamics, paying close attention to underbody airflow and turbulence over the wheels. The new model also benefits from active shutters that close the grille.
The changes allow the new Jetta's engine to maintain 150 horsepower and 184 pound-feet of torque, unchanged from the previous model year.