Hmm tricky one.
I'd go for property if I wanted to make money.
Cars and classic cars can be a money pit, but are good fun. However, if you buy a mint classic and use it - it will rust. You'll then have to invest money in getting it back to mint condition. If you wash a classic, it will rust. Drainage in older cars isn't the best, water hangs around. Oh, they can leak too! :-) If you don't use them, things will seize up. If you need to repaint a classic, unless you can do the work yourself you'll be looking at a fair few 000s. But that goes for any car really.
If you can find one that appreciates then that's a bonus! The classic Fords - Cortinas modified by Lotus, Ford Sierra Cosworths with race heritage are worth good money and going up. The odd barn find can be sold for good money, but it's always mint examples that command the money. And if you use those cars, they won't be mint.
But good luck with whatever you decide to do.