I maintain full coverage on mine as well. Even at 348,000 miles there's not a speck of rust on the vehicle and it has never had any sheet metal damage - only the bumper covers. With State Farm, it's only $13 more per year to take the collision deductible to $250 instead of $500. I've got zero deductible on glass and comprehensive though. My question to the insurance company is always "Can you find me another 2002 as clean as mine, that has been fully maintained to BMW specifications, for the dollar amount you claim its worth"? (It's how I always get OEM windshields as replacements )

2002 X5 3.0 348,500 miles
2014 428i 41,000 miles

2004 325i Sold at 123,600 miles
2001 325i Sold at 66,000 miles

1970 Firebird Under restoration (Insured for a fixed value)