I wash the car insider and out with a normal car wash. Then polish all the pastics with Mer PVC polish. You dilute it , spay it on and rub it up with a soft cloth. Does a nice job of the scuffs inside round the seat and pedal areas.
The crap inside will be mostly diesel particulates if they are oily, prob from being in the city (just imagine your lungs). I use wipes that we have at work, but baby wipes work well on greasy stuff. I tend to hose the floor down in mine to get the mud etc out.
this hasn’t happened to me with the Twizy, but my last EV had a throttle that was a simple potentiometer, and it could not cope with being drenched. It’s hard to imagine that Renault wouldn’t have waterproofed it from BELOW but perhaps the Twizy throttle is vulnerable to inundation from ABOVE.
Joking aside, I find the local steam-cleaning hand car wash are pretty good. Instead of using pressurised high-volumes of water, they use steam-cleaners, which are far less invasive and don’t use as many hash chemicals.
This works particularly well on the inside of the Twizy, where you don’t want huge amounts of moisture.
The only downside? They use a back-to-black style product which keeps the interior areas black and the mudguards etc black. It works a charm, but sometimes leaves the floor a little slippery!
Another good bet are the big armoral wipes you can get for cleaning the dashboard etc. I use them on all my cars with great results!