It took almost an hour and about a dozen specialized tools to take the negative post off my battery in my Chev Lumina car and more was required if I wanted to remove the battery from the car. This seems like a deliberate attempt to make it hard to do a simple thing that I might need to do in a snow storm with makeshift tools. The fuel filter and four of the spark plugs and the distributor require the engine to be pulled to access them. I have yet to find the oil filter (and I have the new replacement for an example).
I replaced my clutch on my Volkswagon van using two crecent wrenches, a flat head screwdriver, and a furniture mover with a few wood blocks and the vehicle's supplied jack (to put the 70 pound motor on wheels when pulling it away from the clutch) and the whole process (pull engine, change clutch parts, put everything back together) took me one hour and will be faster if I ever need to do it again.
There is for you two extremes of engine design. I bought a Renault (not sure how that is spelled) car from a guy that really likes them. They consistantly are the car of choice for many road rally winners because of their simple little goal: as few bolts as possible to access every part of the engine. The newer ones even go further and specify three bolts needed to REPLACE any part... including the clutch! On the older one I had, I replaced the cam shaft with 9 identical bolts and the head gasket seal was reusable. This may be further then needed but I like it.
I am going to start shopping for a high efficiency vehicle but I want to be able to fix everything myself with a basic set of tools. I generally like Toyotas for fuel efficiency but they use way too many different types of fasteners. I replaced the heater fan and had to remove about 30 screws and bolts... Not too big a deal BUT I had 16 different types of heads to deal with (hex key, torx, flat, Philips, square, bolts... all sorts of sizes). I was looking at a flyer for a car manufacturer (can't remember which one) as well as a Toyota flier of their latest models. The Toyotas did have better mileage for the equivalent vehicle from the other manufacturer but the other brand were not too far behind and none of them had anything special (hybrid or electric assist or unique drivetrain or transmission) except a much more efficient engine. The picture of the engine they showed in the flier showed top-mounted spark plugs (easy to get at) and the oil filter indented in the oil pan (should be easy to get to from under).
The threat of a solar storm causing high magnetic flux and static charges here in earth makes me insist that any vehicle I buy needs to have non-silicone-based electrical components and controls which means no digital emissions computer or electronic ignition or modern alternator (need to use the old generator with relays in the regulator so no diodes and no electronic circuits). This will be a tall order for most manufacturer's designs. People who work near radio telescopes are not allowed to have any electrical parts on their vehicals so they have hand cranks to start them and use diesel engines without glow plugs and even have no lights and battery so have mechanical signal indicators (or just use the arm out the window) and fuel lanterns for any night traveling. I need to ask if any of them has a more modern vehicle converted to be electricity-free (instead of the stuff from the 30's and 40's they were using). My idea of a pnumatic hybrid (use pressurized air instead batteries to store the energy from the engine and energy recovered from slowing the vehicle) came from learning of the radio telescope worker's electronics-free vehicles. With nothing but pipes and pneumatic controls (including analog pnumatic computers like fighter jets use so they are not disabled if flying near a nuclear explosion with it's extreme magnetic flux bursts), it will be easy to fix and yet maintainance free.
Looking at a chart of where the energy goes in a typical 70's car, almost 80 persent of the fuel's energy is lost before it turns the drive shaft. Hybrid designs and
aerodynamics and lighter vehicles only work at reducing that 20 percent of energy coming off the drive shaft. Efforts should be concentrated more heavily on better engines (as that manufacturer I can't remember is doing and almost matching mileages of Toyota's hybrids and such) and diesel engines are better (run on vegitable oils, needs no spark plugs). One promising design is the Quasiturbine engine which promises to have oil-free engines with fewer parts and can run on a wide variety of fuels without modification (including diesel).
Will I find an electronics-free high efficiency vehicle that I can fix with a few basic tools or will I have to build one for myself?