Drivetrain

One good configuration would be to have engine drive to the front wheels and an electric motor drive the rear wheels and recupricate energy when stopping.  This is quite different from the Honda and Toyota hybrid designs, since the engine and motors are totally separate.  One system can completely fail and the other system will still limp home.  By making the rear wheels "electric drive compliant", the system will be removable or addable as an option.  It would take very little designing to do so; just add some gears to the wheels, mounting holes in the frame, battery space in the trunk, and computer compliance. (VJC)

Body

The body will be an adapter between the frame and the accessories (items such as seat, controls, doors, console, windshields, etc.)  The mounting for items like doors and windshields probably can't be completely standardized.  One option is to make a standard for doors and just let body manufacturers make their own doors if they want something non-standard.  It would probably be best to leave most of the wiring up to the body manufacturer. (VJC)

I understand that one size does not fit all.  Sometimes you want a small engine in a small engine compartment.  It would be too troublesome to make one single body standard that requires every car to be able to accept every size engine.  However, the answer is very simple.  Require only that the mount points be standard.  A body that is made to use a smaller engine will simply be compatible with a certain standard size and smaller.  Frames can also be made flexible.  This part I have not thought of in detail yet.  The basic idea is to have one stage of bolt holes at the frame, to add adapters to it to drop down the size, to add motor mounts to it, and finally to add the engine.  Then, frames can be thinner by either skipping a step (already being adapted for smaller engines), or using different adapters for different standard widths.  The vast majority of people would be completely satisfied with only, say, ten different frame widths, as opposed to the hundreds (or maybe thousands) of slightly different widths that exist now.  By unifying widths to common points, a very large part of the design process is made much simpler. (VJC)

Wiring

The first step will be to make a wiring harness between the engine compartment and the cabin.  It will attempt to route all command functions to a computer inside the cabin.  This wiring harness will access all sensors, powered devices, lights, the alternator, and anything else that might need thinking.  A computer inside the cabin (much more powerful than what's currently used in cars) will control everything.  The owner will then be able to customize everything.  If the owner wants the seats to rise up when getting out and lower after getting in, he just programs the computer. (VJC)

After making the first unified connector (probably long, screw-in type), additional connectors can be added as needed.  For example, not all cars will need access to a camera in the grille or police lights on top. (VJC)

Engine

General

The standards will evolve.  There will be no enforcement of standards, and as changes are needed, changes will be made. (VJC)