How do I get my boyfriend to clean his car tf out?

Look, I know it's his car and everything but he has PILES of trash in the back, banana peels, candy bags. When it comes to us driving somewhere or when he gets asked to drive someone, he ALWAYS asks if he can use my car because his is 'dirty' and 'embarrassing'. Like yeah, so clean it. When I tell him no (because he damaged my car 3 times already when he used it and I dont want him driving my car) he gets pissed off. Like tf?
How do I get my boyfriend to clean his car tf out?
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