Currently, the amount of money sinks are low, and you can straight buy off everything you need. What if you couldn't?
That's where salvaging would take part in. You can salvage(destroy) your own vehicles permanently, in order to gain vehicle parts (1-3 different parts) There's common, rare and very rare part that you can get each time you salvage a vehicle. The costier vehicle, the better odds in getting the more rare parts.
Why would you salvage your vehicles?
We'd remove buying V8 and all that affects the vehicle handling/speed and add them as salvaging rewards. The only way you could be able to get V8 is by salvaging your vehicles, forcing you to buy different vehicles and scrapping them off in order to get parts. The better the car is, the more parts it requires. This would make V8 and the other add-ons way more valuable, and would give people something to aim for. Salvaging could also be used to make your vehicles bit more resistant to bullets.
This could also work in weapons. You could salvage your AK-47, M4, Snipers in order to get weapon parts. Having enough weapon parts could allow you to construct small amounts of armour, knifes or satchels. In my opinion, this would be way more interesting way to gain valuable guns, other than just buying them straight off from a shop
Forces you to buy way more vehicles in order to get V8, one vehicle won't cut it. You can destroy weapons to gain parts, which you can use to put V8 in your vehicles. Same for weapons. Puts some RNG in getting the vehicle parts, and selling V8 vehicles would be way more valuable in order to avoid having to roll for luck. Also puts a good market for vehicles