I haven't washed the car since the winter (was away for few weeks). I have an under chassis lance and usually use this lance to get rid of the winter salt. But is there any protective coat/layer under the chassis of the 991 that could be damaged by the pressure washer.

Thank you

(Car is UK specification and lots of wet road where I live)

 

There is nothing on the undercarriage of mine. I think you will be fine. Spray and clean away!

 

If you look under the car, you'll find there are underbody panels covering all but the extreme front of the car, some of the engine area, and of course the wheel carrier suspension at each corner. Rest of the underside are completely covered. So spraying a strong stream of water along the underside of the car shouldn't have any negative impact at all. Those panels are a very strong / stiff material so unless you stick the lance up over them somehow you probably can't cause any issue. The only areas I would be careful is around the engine.