The best fuel-economy ratings of the 2013 GS lineup are reserved for the GS 450h hybrid. As for the GS 350, it's scored by the EPA at 19 miles per gallon city, 28 mpg highway, and 23 mpg combined. Lexus says that's a 2-mpg improvement over the prior generation.
While that's far from class-leading, it's not at the bottom of the pack. Lexus carried over the GS' base drivetrain and its six-speed automatic, while other luxury brands have updated their offerings to include seven- and even eight-speed automatics. Even so, the seven-speed Infiniti M37 is rated lower than the Lexus GS 350 at 18/26 mpg, while the Mercedes-Benz E350 is much higher, at 20/30 mpg, and the eight-speed Hyundai Genesis sedan is pegged at 19/29 mpg.
When it's outfitted with heavy all-wheel-drive gear, the GS 350 is downrated to 19/26 mpg.