I don't know of very many fuel injected cars with intake air preheaters anymore -- main rational for heating the intake air was to prevent icing in carbs set up for very high atomization and efficiency (you can have good atomization or anti-icing, not both, I think).

All the MB D, K, and KE jectronic systems are configured to pull mostly oustide air in, and in my personal humble opinion, could be called cold air intake systems. The M117 does pull in some hot air from the oil cooler, but I suspect the majority come in through the vent under the hood around the ECU.

When you figure in filter efficiency and engine longevity (for which a very good air filter is required) I don't see how one would gain much by messing about with the intake unless actually racing the car on a track. For road use, I'm more than happy to let "preformance oriented" drivers burn up their engines with dirt at stoplight drags. I'm more interested in getting to work in one piece without a breakdown on the way!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!