Recently, I made a trip down to my local hobby shop and found some older Athearn station wagon and sedan car kits. I just happened to have some paints left over from a 1969 Camaro kit I attempted to build a while back, so I used them to touch up those vehicles.
If you ever find those at a hobby shop, you can use some Testors spray and enamel paints to improve the looks of them. I used 2 small jars of red and silver enamel paints. You can use silver (or whatever color you want) to paint the rims/hubcaps and red for tail lights (I suppose you could use silver on the front and rear bumpers, but i didn’t). I use toothpicks and superfine micro brushes to apply them (toothpicks for tail lights). For the spray paint part, I used a small can of Testors (not sure which type in particular. The label was torn off) metal flake blue for the station wagon. Of course, it will take some time to dry unlike the enamels, which dry pretty quickly.
Here are the finished products. Kinda messed up on the sedan wheels since I ran out of micro brushes, but it still looks ok (didn’t paint sedan).

It takes a steady hand and patience for those tail lights and wheels, but in the end, the cars will be nicer to look at with all extra paints added; Something you can do in an evening if you have some vehicles you want to improve the look of.