Mach 4 (WildStorm)

The Mach 4 is a vehicle featured in the Speed Racer franchise, most prominently in the 2008 live-action film as the car driven by Rex Racer before leaving his father's racing team. This vehicle is the predecessor of the Mach 5 and the Mach 6.

WildStorm/DC comics
Eight years after Rex Racer died, Dr. Bent Cranium and Henry Racer develop the ER-X, a powerful racing engine that would serve as the predecessor to the infamous GRX. The engine is given to Pops, who installs it into the Mach 4, with Hank Racer as the test driver. Buck Condor, who sought to steal the engine technology for his own selfish gain, sabotaged the test run, resulting in a crash that kills Hank.

Johnny Lightning die-cast toy
A limited edition die-cast toy car of the Mach 4 was produced in 2000 as part of Playing Mantis' Johnny Lightning toyline. It was only available by mail order. It could be acquired by sending in $3.99, $3.95 S&H fee, and two proofs of purchase (either two UPC codes with complete cardboard backing or cash register receipts). The die-cast car itself is a repaint of the Mach 5 in red with a white "M" in contrast to the white body and red "M". Along with that, the headlights are painted on top of the Mach's side-noses. Along with that, it has a black number 4 in a white circle with a thick black outline.

The Mach 4 is one of the most coveted Speed Racer die-cast cars in the Johnny Lightning line-up, often fetching high prices on the internet.

Trivia

 * The ER-X engine used by the Mach 4 in the WildStorm/DC comics is a reference to the GRX's original Japanese name.
 * The engine is compact in size yet capable of torque up to 16,000 RPM providing acceleration described as "motorcycle-like".

2008 film
The Mach 4 was featured in the film as Rex Racer's car for professional-level races prior to becoming a cheating driver for Uniron and faking his death in the Casa Cristo Classic 5000. It is a single-seated race car like the Mach 6, but is red and the bodywork resembles more like the Mach 5. It has a white version of the distincive 'M', along with its racing number also in white surounded by a white circle. It has tailfins like the Mach 5, but there is also a third central fin at the back, all connected by a single wing to form a spoiler. The rear fenders also feature what appear to be air intakes or ground effect channels. Not much else is known about this vehicle, except for the fact that it has a rear-wheel drive layout, indicating that it is not a T-180 like the Mach 6, and is part of an older generation of race cars. Added to that, the rear wheels are fixed but also feature a joint system somewhat resembling that of the T-180.

The Mach 4 was also available as a toy in Happy Meals at McDonald's, as well as a Hot Wheels car in certain sets.