"Restoring" isn't what you want to do, but MAINTAIN it in proper order, do proper servicing, preventive maintenance and try to tackle small problems before they get big. Fluid changes are important, as is proper lubrication of the bearings and fittings that do need attention (many newer vehicles have sealed bearings). Let's start with a 2002 Chevy 1/2 ton 4x4, it needs both differentials serviced, the front bearings serviced and maybe new axle seals along with common items. Now, the 4L60 goes out in it, because automatic transmissions DO wear out, and you can do the work yourself or get it rebuilt and specify the parts going inside. Because knowledge gains and technology changes happen during the lifecycle of the transmission (or engine) you benefit from better than the factory original parts. Now, your 5.7 Vortec engine starts to have issues at 231,000 miles, it's an easy engine to rebuild and the block is near bulletproof so a rebuild is worthwhile, just like the tranny, and you can get ARP studs instead of torque to yield head bolts, better valve springs and a different cam and gain 100 HP over the stock build for not all that much over "stock numbered" parts. You can check your local market for the cost of engine or transmission builds if you don't want to do your own. Can't say the same for Dodge and Ford trucks currently, their main engine line-ups have more fatal issues than the Vortec/LS. Not saying Ford and Dodge aren't worth getting, but they need specific attention to certain systems.
OK, front-drive car, most you'll have to change the timing belt if so equipped or sometimes deal with a slack timing chain, both can lead to AWFUL engine damage with interference type engines where the valves can slam into the pistons. Even with non-interference engines, you need to swap belts per recommendation and swap out the water pump with it because you need to pull the pump anyway. For some cars, it's easier to pull the fender/inner fender set to access the front of the engine too. Have to be aware of CV joints going out and struts needing to be replaced, rack and pinion maybe too, but most are affordable now, and a rack can be rebuilt. If an automatic tranny or engine needs work it is often easier to drop out the whole sub-frame than to yank them out the top, BUT you need the right logistics for that too.
So, then you have the sub-systems like HVAC, fuel pumps, etc.
Think biggest killer is always rust, you can swap out components but if your truck frame or unibody has extensive rust issues it's hard to justify a lot of re-investment. BUT, if you do have those concerns you keep on top of washing/cleaning, make sure all the weep holes behind the fenders and in the door stay open and be diligent. There are rust abatement and encapsulation produces and welding is a recourse if needed. I don't live in the "Rust Belt" so I could probably keep a rig on the road for a good while, but that means swapping out seats and carpets eventually (or rebuild the seats) and other stuff.
Hate to say "planned obsolescence" but vehicles normally do have a certain limit of endurance, and I swear newer ones are more fickle than ever. Personally, my choice would be a 72 Chevy/GMC 3/4 4x4 because they are simple to deal with and you can use almost any combo of engine and transmissions GM produced in them.
But it comes back to Toyota and Honda families of vehicles with some European ones that can do well with careful ownership for many people, and while some US cars are decent enough, I don't drive one currently. I AM putting together a 1955 Ford F-100 resto-mod ...