318 MAX fuel economy builds?
My own custom electronics! I can make quick test circuits on generic proto boards, which may last a week or 20 years. Something in the category of "reliable" requires automotive grade components (which are in short supply right now) and a professionally made PCB board (which I get done all the time, but they cost a lot of money in small batches). I use PIC MCU's exclusively, and the MPLABX IDE for programming them.