1) The stock (original equipment) air intake is a cold air intake. I haven't taken apart an E70 intake, but this was true on every other BMW I owned, so I suspect it is true on the E70 as well.
2) The restriction in the stock intake is negligible.
3) Aftermarket CAIs commonly take their air, paradoxically, from under the hood. Those that do are in fact hot air intakes, despite the marketing labels attached to them.

I have no knowledge of the first two points where the BMW is concerned. And agree with the last. My Twin-Turbo CAI is a custom modification of the stock box and and it breathes true cold air from outside the engine compartment; it does a great deal to lower both the charge and inter-cooler body temperatures as measured before and after installation.

I just wanted to know why there seemed to be a blanket "not worth it statement."

Thanks

I honestly like the extra bit of engine sound from them when u put ur foot down
I had an AFE one on my 3series and although I'm sure there wasn't much, if any HP increase it sounded great

Actually that is not true- at least the assertion that somehow trubo versus non-turbo impacts the question.

If a car has an intake that sucks warm air, then a system that sucks cooler air will be a benefit.

HOW MUCH of a benefit depends on (1) how much cooler, and (2) how much more resistance (static pressure) the CAI creates.

Just becuase a mfg calls something a "cold air intake" does not make it true. They toss up a cooked dyno, and people plunk down $$ becuase they like the sound....


On the X5? You should post the data. or are you talking about the RX7 which has a poorly designed intake from the factory?

Also, could you explain how a cold air intake changes the 'intercooler body temperature'.... to change the IC temp you need to have an air-to-air IC AND change the airflow into the intercooler, or make the intercooler more efficient.

On turbo cars, changing to "less restrictive" air filters/intakes usually does nothing, as the turbo can pull as much air as it needs (generally they are dumping/limiting the pressure anyway). An NA car WILL benefit from less restriction as it will use all the air it can get, but most facotry systems are already pretty well designed.


Anyway, unfortunately nobody will put the engineering effort into blueprinting the X5 for tune, intake, etc, etc....you'll find shops that toss half-assed stuff out, but a careful mapping (a la Dinan) will not be done- no market. IMO