The 1999 GS 400 was just the second installment of the vehicle, so there were no changes from the 1998 model-year offering. The car retained its powerful, 4.0-liter, V8 engine.

That engine produced 300 horsepower and offered acceleration from zero to 60 miles per hour in 6 seconds. Later, 4.3-liter versions of the GS 400 did not improve significantly on those numbers.

"You cant fix perfection," wrote one owner when asked what improvements he'd like to see on the GS 400. Safety-conscious drivers were a bit put off by the rear-wheel drive, but performance-minded driving enthusiasts would not have accepted the GS 400 any other way.