My 2015 911 has a rear spoiler over the engine that is totally impossible to ever see while driving if it is deployed or not. I can check that it does work when parked if I deploy it on purpose. But it is total faith that is has deployed during driving. If it has deploys automatically, there is no way that I found to determine what position it is in. I also couldn't find any information about what speed is it suppose to deploy, and what speed is it suppose to close. Does anyone know some of this information?

 

Depending on the vehicle speed and the position of the slide/tilt roof, the rear spoiler extends automatically at above approx. 75 mph (120 km/ h) and retracts again below approx. 50 mph (80 km/h).

If you have a sunroof (and its opened), the spoiler deploys at an even greater angle.
You can barely see the top edge of the deployed spoiler in your rear view mirror.

http://www.porscheownersmanuals.com/...ting-principle

 

As “dux” discussed, when engaged automatically, the rear spoiler obscures the bottom edge of view from the rear view mirror.

 

I have never checked my 991, but on my 997.2 I actually had my young son ride in the back seat and watch, and tell me when it went up (120 km/hr) and down again at 60 km/hr

 

it is a lot easier to see it on 997, but not 991. but if you move up a little you can see the upper edge.

 

Best way to see it is very late afternoon with the sun at your 3 o'clock low. Look at the shadow of the car at your 8 o'clock low. Easy to tell when deployed. Don't forget to check your 12 often!

 

I only bought my 991 2CS because I could see the spoiler go up and and up again and down too! If you have a cab, you need someone following you with a camera.

 

It will trigger a dash light if it does not work.

 

Better view on a Turbo 991

 

On my 991S, I couldn't see it even if I sat up in my seat...with the GTS, I can see it deployed at the lowest angle. Maybe due to the wide body?

 

Could be you keep the seat in a lower position than I do.

I believe that in the GTS the spoiler always deploys in the higher position that mine (C2S with SPASM) goes to when the sunroof is popped.

 

I thought this was only for cars with Spasm, I only have pasm and when I tried it manually I didn’t notice any difference in the spoiler position.

I have tried many angles with my exterior and interior rear view mirrors and have yet in 5 1/2 years ever seen my spoiler ever go up or down automatically.

 

Correct. It can be seen in the rear view mirror in the turbo cabriolet in the first position at 125 kph, and easily seen in the fully extended position at 150 kph.