Your mom's BF....
GRRR... he should be slapped!
That green Convertible is model 69, made 1961 - 1964. to clean the hood I'd use a Mr. Clean "Magic Eraser"for the marks, then polish with Brasso metal polish. Brasso has fine pumice in it, making plastic sparkle!
You may be able to get some softness back in the bag with some armor-all. I'd also suggest washing it in the washing machine, HOT WATER, gentle cycle...use about 1/2 cup of clorox bleach, and maybe 1/8 cup of laundry detergent. If your washer has a warm rinse setting use that too. When done, stretch the bag back into shape and hang to dry...
Good luck and let us know how it turns out!