Called the ARX-04b, it's Honda's first closed-cockpit LMP2. Like previous LMP2 and IndyCar projects, it's a joint development between HPD and Wirth Research, and packs Honda's HR28TT engine – a 2.8-liter twin-turbo V6 based on (and using many of the same components as) the J35 engine you'd find in a contemporary
Acura. Designed to exceed the latest safety regulations, the ARX-04b features low-drag bodywork, quick-change front and rear panels, the same locking fuel filler system that Honda pioneered for Indy, top-exit exhaust to meet noise regulations, a 75-liter fuel tank and a gearbox that can easily be optimized for individual circuits.