Cars haven't just had one ECU for years. An average car now has at least 8 ECU, something like an S class Merc can have 60 plus. Everything is a control unit even down to rear view mirror, headlight switch, each door, abs, air suspension, active roll bars, active cruise, parking sensors, airbags, USB audio, phone, tv, radio, radio controller etc etc.
You lot have in easy with alarms.......
(light the blue touch paper)
Anyway what alarm am I buying tomorrow?