Share your insights or perspective on the financial matter presented in the input.

mortgage vs car loan vs invest extra cash?
A point that hasn't been mentioned is whether paying down the mortgage sooner will get you out of unnecessary additional costs, such as PMI or a lender's requirement that you carry flood insurance on the outstanding mortgage balance, rather than the actual value/replacement cost of the structures.  (My personal bugbear:  house worth about $100K, while the bare land could be sold for about twice that, so I'm paying about 50% extra for flood insurance.)  May not apply to your loan-from-parents situation, but in the general case it should be considered. FWIW, in your situation I'd probably invest the money.