The 1990 Mercedes-Benz 350-Class, with its turbocharged diesel engine, continued the tradition of Mercedes diesel engines in the U.S. The turbocharged diesel was first introduced in the U.S. in 1978 with the Mercedes 300SD, and proved more efficient than standard diesels as well as more powerful at higher speeds. Generally, the acceleration with diesel engines is slower than with gas engines, but diesels get better gas mileage. They're still popular today, particularly with drivers interested in switching them over to biodiesel, a blend of traditional diesel fuel and vegetable oil.

The 1990 350-class was available in two configurations: the 350SD and the 350SDL, both sedans. Both came with a 3.5-liter, inline 6-cylinder diesel engine that generated 134 hp. A 4-speed automatic was standard for both models, as were power windows, power door locks, anti-lock brakes, and air conditioning. The SDL came with an upgraded package, including leather seats.

Other standard features and options included bucket seats, a rear-window defroster, fog lights, power sunroof, power seats, power steering, and alloy wheels.