If you are using the salvaged robots mod, minireactors become a much more viable source of power. Plutonium cells can be found by disassembling the integral minireactor you can get from taking apart broken robots. you get 10 cells per reactor, enough to fully fuel up a vehicle reactor.
I use nuclear electric/solar hybrid as the power source for my tank. Solar alone won’t work because my tank needs 4 enhanced electric motors to even move, and has 2 floodlights, which are power hogs. Not to mention all the lasers. The combination works pretty well, but I have to have 4 upgraded solar arrays (not panels, arrays) to recharge in any reasonable time period, which take up whole interior tiles.
I would recommend having lots of power storage if you go electric, or a backup diesel or gas engine in case you run out of juice.
Redundancy is also a good thing. If its an important part, having more can’t hurt. You can turn off extra engines so you aren’t wasting more power or gas, or to switch between gas and electric engines. For other things, especially sensitive parts like cameras or lights, its good to carry some spare parts around. I usually carry 2 spare cameras and floodlights, and a few armor plates, just in case. A welding rig is ESSENTIAL for on the go vehicle repairs. Save your duct tape for better things.
Important and vulnerable parts like fuel tanks, batteries, or engines should be placed at least 1 tile from the edge if possible, far away from potential points of impact or attack. Away from wheels too, in case you hit a landmine. In addition to redundancy, it is also a good idea to spread out your vital components if you can, to prevent any given hit or crash from completely disabling your vehicle.
If you have a lot of internal tiles without something occupying the lower layers, I’d recommend filling them with 60L storage tanks for the various liquids. Not having hundreds of bottles and gallon jugs filled with crap really helps cut down on stored volume in your stowboards, floor trunks etc.
Also, Shard’s Misc. Mod has some very good storage items. Internal 200L tanks so you don’t have to worry about using external ones that come with the base game; those damn things fall off if you bump into something, and spill all their contents. And the storage battery array, which is equivalent to 8 storage batteries, but takes up a whole tile.