Money from Car Parts
The sales of used light vehicles in the United States came to around 40.8 million units in 2019 alone. This is according to statista.com . It means that more and more replacement parts like the mundane battery, fluids, tires, belts will be needed to maintain cars especially for older ones.
That is why it is important to learn the knowledge of how to maintain cars even if just a hobby because you never know when you are going to need your car fixed but there is no mechanic available for your situation. It is also a skill worth knowing as there are about 1.4 billion cars in the world in 2018 alone according to carsguide.com.au that if you ever needed a job you could consider a job in car maintenance.
If you are more interested in the physical appearance of a car you can become a detailer, panelbeater ... etc. and you can even sell bodykits, tinting, wraps, custom rims ... etc. I had a look at my cable channels and it seems that car maintenance and "pimping" channels are all over the place attesting to the great demand for these products and services.
These car guys in the shows even become celebrities in their own right. I recently saw YouTube videos of motorcycle scooters which are popular in Asia being given the makeover and they look magnificent.
You can Google "pimped out scooter" and just look at the images and you can see that there is a market for it especially with the growing popularity of motorcycles especially with people who do not have access to car ownership. You can also make money by rummaging through car yards and try selling used car trimmings for old cars who used to have plenty of chrome parts and emblems.
Old car collectors pay a premium for these rare parts now. All you need is a keen eye for these old parts when you are visiting old car yards and vintage car barns.
Conclusion
There are now plenty of cars in the world today numbering in the billions. Many of these cars would be maintained for a long time and would even be preserved as classics. Many also would be accessorised and reworked and this presents a huge business opportunity for those who are able to supply these products and services. Many of these providers have even become profitable and famous in the process.