[Sales@Evolve]

IAT's on the road do not rise during an acceleration run.

We have tested this numerous time under both freezing and 25+ degC temps (doesn't get much hotter than that in the UK).

An E9x M3 will show ambient +1-3 degC IAT once in real world conditions. Under full load and high speed, ambient = intake.

This is not just through OBDII but also with 4 k-type thermocouples placed from the intake scoops, inside the intake muffler and the opening of the plenum itself. The IAT sensor does not heatsoak on S65 setup either which is very nice to see (not IAT relocation kit is needed!). Infact, when you measure with the very quick reacting k-type thermocouples in various locations it's very interesting! Especially when you compare to the very slow reacting (in comparison) IAT sensor fitted inside the plenum.

Under idle conditions IAT's will rise rapidly no matter what. The frontal air scoop which takes air from just infront of the radiator rapidly warms up the temperatures in the intake muffler and heat from the recirculating oil breather system into the plenum itself.

On a dyno it's however a different story with the majority of dyno cells. The IAT's are significantly higher than in real world conditions with inadequate air flow.

EDIT - IAT's on the road can rise on an acceleration run in the case where you are behind another car at WOT. The exhaust gasses go straight into your intake system. Not great quality of air either! :-)