Lol, well it is more expensive anyway
I don't see all those SMD's being particularly DIY though.
edit: check that, the STM32F4Discovery is like $14!, I've only looked briefly at the ST processors, and would be eager to push it to its limits with asm blocks, 6ns per cycle?!? You might need that for CDI/GDI
FYI, someone made a diesel ECU (audi TDI) from an arduino
Arduino powered ECU for diesel engines - Arduino Forum