I have one made by Cabrio Shield I think.
It has "tabs" that tuck into the door shut lines and lips into the boot making it secure once it's on,meaning it can't be removed again untill the doors and boot are opened. It's only intended for use over short time periods though,not for long term storage.
I use it in summer as well as it shields the hood and interior from damaging UV light and heat.
As long as the car is clean before you put it on there should be no damage caused to the paintwork,same principal for the full cover I also use and so far neither cover has caused any paint damage.
I know some people may say these covers are Satin's work,but when you don't have a garage or car port I personally recommend them. Just ensure you don't put them on a dirty car......simples

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Steve.