Many of the suggestions on this list call for considerable skill and creativity on your part, as they generally require disassembling parts of your vehicle and reassembling them in another form. If you’re not up to that lofty challenge, or don’t have a handy friend who is, said options may not be viable.
However, there is one option that even those with no practical experience working with cars can undertake. All you need to convert the cargo bay of a truck or a car’s engine compartment into a flower bed is a handful of standard gardening tools, a few bags of dirt, and a packet or two of seeds.
You will, of course, also need the area in question to be empty and relatively rust-free. You may want to line the bed or engine well with gardening mesh or other growth-promoting materials before you start, just to give your seeds the most hospitable possible environment. Once you’ve done that, just fill the space with soil, drop in seeds, and you’ve got an automotive garden.