Grx

GRX
The GRX is actually a type of engine in the Speed Racer universe (originally called ER-X in the original manga) and makes its debut in the episode The Fastest Car on Earth (Part 1). This engine propells the car as so fast that it was responsible for the death of several test drivers.

In the Speed Racer Film the GRX is the name for the cars in the World Racing League (WRL) as they all feature engines of such magnitude. One of the most famous of these is Royalton Industries #66 GRX driven by Jack "Cannonball" Taylor.