Seppuku

The Seppuku is Kakkoi Teppodama's T-180. The car is part of the Musha Motors team, which is a major company in the Speed Racer film. It is featured in the Grand Prix race near the end of the movie.

The Seppuku is playable in the PS2 version of Speed Racer The Videogame.

Technical Details
This yakuza-themed car is part of the Musha Motors team, which means it's very likely that it uses an inter-positive transponder as its engine, similarly to Royalton Industries' GRX.

Background
Kakkoi starts the race from the midfield and stays close with the pack into the Zebra Halls. He was the first to spot Speed, and he slams him into the rest of the field.

He is assumed to be far ahead of the remaining pack as he was not seen until the final lap. He is occupying the lead when Speed Racer shows up. Determined to not let Speed win, Kakkoi teams up with Grey Ghost to try taking Speed out on the final stretch. Kakkoi slams Speed and Ghost with a sliding attack to no effect. Things continue to flare between the three until Speed finishes the job by wedging his car into Kakkoi’s, and then swinging the Seppuku into the Fumée, causing both Ghost and Kakkoi to wreck.

Trivia

 * "Seppuku" (often referred to as "harakiri") is a Japanese suicide ritual that is performed in order to restore lost honor.
 * Seppuku has the same body shape as Tortitude Tiga.