[PF1]

Just a question for those of us who already have the car. Driving behind the car I noticed the right side exhaust looks different from the left side. So had a closer look and seems that the right exhaust has a metal flap inside it. Does anyone know when that opens? Full throttle, or Sport mode? This is the petrol 25i engine.

[Pretender]

Originally Posted by mynewx1

Just a question for those of us who already have the car. Driving behind the car I noticed the right side exhaust looks different from the left side. So had a closer look and seems that the right exhaust has a metal flap inside it. Does anyone know when that opens? Full throttle, or Sport mode? This is the petrol 25i engine.

You're probably a first time BMW owner. This exhaust flap has been in BMW cars with dual exhaust pipes for years. The flap is intended to provide enough back pressure for more low-end torque when you run at low RPM. If you pay attention to it when you warm up the car in the morning, smoke only comes out from 1 pipe. When you rev up, it opens. This flap connected to a little hose that blows or sucks air for open/close mechanism. Look under the car and you will see it.

[PF1]

Thanks for your reply and explanation! Yes it's my first BMW so didn't know about this feature before! In my other car one side of the exhaust gets more dirty so maybe has a similar system but there's no flap visible from the outside.

[AusF20/F48]

Originally Posted by mynewx1

Thanks for your reply and explanation! Yes it's my first BMW so didn't know about this feature before! In my other car one side of the exhaust gets more dirty so maybe has a similar system but there's no flap visible from the outside.

Yes, Pretender is correct, and it works in conjunction with the choke control when the vehicle is warming up.
Though Pretenders reply could have been a little less condescending