This is exactly the same problem i have! Tried explaining it but everyone always said that it is normal and that the car is just letting out alot of heat as normal cars do. But i have driven alot of cars and none of them let off steam when it rains and sometimes it is so much that it looks like the radiator over heated or something. Even without the rain, i can see the heat coming up when stopped at a light either from the front or sides. I really dont think this is normal and maybe just a fault with some of our cars. I already tried replacing the radiator cap as some have suggested but i still have the problem.

 

^ Have you considered that just because everyone's v36 G sedan does the same thing and that yours does too that it is indeed normal? Also, just because other manufacturers don't have steam doesn't mean yours shouldn't. Other cars don't have as much horsepower as ours, so you can't compare them. Our engines is not the same design as in other vehicles. This point is moot.

I don't understand what else you want as proof? Everyone has this steam incident when in the rain. As long as your temperature gauge reads normal and your coolant level has stayed the same it is fine. Our engines and cooling systems are designed this way. I have 75k miles in my car and have no problems with it even though I get steam from my hood too. Stop worrying so much.

Plus, if your radiator overheated, then your coolant will spill over the radiator cap and make a mess and your temperature gauge will go up since your engine would have actually overheated. If your coolant levels stay constant, and your temperature gauge is fine, then stop worrying about it.

 

Living in Canada. this happens quite often. I've had steam come out of grille with the following cars while either waiting in traffic during winter or rainy days.:

Cooper S 03, Cooper GP 05, Wife's 335XI and now with my G35X.

I would say it's normal, none of my cars have had issues.

 

I had it happen after every time I washed my car since day one, so I'd say it is normal.

Nothing to get steamed over.