NemesisUK

Should but sadly dealers/salesmen, of any flavour, seem very lacking in tech/spec knowledge.. If one can speak directly with the technicians, quite often a different story

I have used Gummi-Pflege for many years, great stuff. Excellent at preventing door seals freezing shut...

Those wires look as if they have been cut and repaired. I would have thought factory loom would have been totally wrapped, why leave joints like that exposed? Second image seems to show a loom terminated after removal or non-fitment of an optional piece of equipment. Didn't think looms were multi-purpose, certainly not in Mercs where even just one wire would be missing if an option wasn't spec'd in the build sheet. Obviously I don't have the 30yrs experience of your auto electrician, so just my first impressions

Is this when the PCS suddenly kicks in??

On most models it's possible to use the ACC (or dynamic radar cruise control) in CSC (constant speed control) mode. By default the ACC system will always be set to the maximum separation distance

Two-piece rotors (aka floating rotors) reduce unsprung weight and improve cooling. this allows the friction surface to be made from different materials (steel, or carbon fibre composite or ceramic) The friction surface is separate from the mounting bell, held by bolts, spring clips etc.. The bell is normally from aluminium. Worth noting, in the RC's case the two-piece rotors cannot be separated and cannot be used with steel rims.

I don't know what the GS is spec'd with but the 2019 RC300h has 356mm two-piece rotors and opposed four piston calipers - OS12WS

Is this a Lexus accessory or a 3rd party after-market offering?

Not only bigger calipers (in a rather pleasing yellow/orange colour) but also bigger 2-piece discs 😎 (rears are the same as pre-facelift, just coloured calipers)

If it's one of the electric motors then the hybrid system would be showing faults. Stop guessing and get the car on Techstream operated by someone who knows what they're doing.

The hybrid battery is what spins the engine to start. Does the hybrid battery have any charge? Really needs to have someone with Techstream to diagnose what's wrong, read off the error codes.

I could see some occasions when it might be useful. Clearly the car recognises the fact it's raining, or does it also ask when it's dry? Does the car ask to close the sunroof when it starts raining? Is there an option in the setup menus to disable the feature?

The RC300h everyday! Smooth, comfortable, responsive and exclusive. The BMW is brash and common..

So the ES transmission is different from that in the RC?