Mercedes Benz 1921 Mercedes Rabbit the First visited Jay Leno's garage.

The Mercedes-Benz name we know was founded in 1926. Prior to that, Mercedes and Mercedes-Benz were separate brands, and so was this Mercedes-Benz-Mercedes Rabbit the First.

Owned by Jay Leno and featured in a recent episode of his online series "Jay Leno's Garage," the car was built in 1921 for racing purposes, using a Benz engine originally developed for airplanes and an old Mercedes chassis.

Leno describes this Benz-Mercedes Rabbit the First as a "low-flying airplane," based on a 1908 Mercedes chassis and stuffed with a 1914 Benz 230 hp aero engine salvaged from a plane that crashed during World War I. It is chain-driven. It is chain-driven and uses a modern clutch combined with a Mercedes transmission of the period.

Such swaps were fairly common at the turn of the century, Leno noted, since airplane engines were like larger, more powerful versions of automobile engines. The engines were quite advanced for their time, with four valves per cylinder. However, according to Leno, 1,800 rpm was "about the end of the world" as far as rpm was concerned.

The car was built to run at Brooklands and lapped the British race track at 113 mph. Today, it still "honestly does 100 mph," Leno said.

After its racing career ended, the car went through many owners and was restored in the 1960s. According to Leno, the car was running when he acquired it, but just barely. The water jackets on the steel cylinders were rusted out, requiring a complex engine rebuild, including replacing the jackets with brass ones.

The car also received some modern upgrades. The original drum brakes were replaced with discs and a cooling fan was added. However, the original oiling system was retained, with a chain-driven pump and an exposed drip cup to keep the driver oiled.

In the end, it took about 10 years of on-and-off work to finish the car. Watch the video to see it in action on the streets of Los Angeles.