[Raceboy]

Newer watercooled 911's use Bosch LSU wideband lambda sensors and on part loads still run to reduce emissions, but on higher loads rund rich to reduce the possibility of engine failures (=warranty).

When I tune standalones, I always make the part throttle load and idle as good as possible with fuel economy and pollutions in mind but there is always a compromise (best economy doesn't necessarily mean cleanest exhaust gases).

We have annual MOT that includes measuring emissions so street cars have to pass the test.