Wouldn't ever let mine get to that kind of state.
To me the mechanical health of the car is more important than shiny paint. I am well known on this forum for being allergic to cleaning cars, but the best thing I ever did was get the 'diamond coating' on the paintwork from the dealer - the civic is 10 years old now, and wifes Jazz 8 years, paintwork still looks good even though never been waxed ( I use autoglym super resin polish on plastic headlight covers on out cars about once a month, and they are showing no sign of cloudiness, I also use super resin to clean our UPVC window frames, doors and fascia boards, guttering and downpipes once a year ) I have used Autoglym bumper and trim gel on parts of the cars and it works well.