Hot rodders have done crazier stuff than this but with uni-body construction it would require the services of a very talented and well equipped body shop.
You could probably achieve getting the car down to 60% of initial width. A lot of it depends on where your engine sits. If it sits ahead of or behind the fron wheels you are good to go. If it sits between the wheels you are stymied.
Maybe a better and certainly still radical move would be to chop the top, if you are short enough to live with a low top sill.
__________________ 2000 Ford F-350 SC 4x2 6 Speed Manual
4" Slam
3.08:1 gears and Gear Vendor Overdrive
Rubber Conveyor Belt Air Dam
I envisioned something like the chopped Metro except I wouldn't stop at the roof. I'd split the whole thing down the middle - 60% of original width as previously posted sounds about right. Since I'd be going to electric I wouldn't need as much room as the engine requires but I don't know if that would crowd the transmission. I'm a big fan of Venture Vehicle's leaning trike so I wouldn't be opposed to a three wheel design except with three wheels I couldn't license it as a car and it couldn't pass as a modified motorcycle either. The airplane canopy idea would be cool but I think I'd have to leave the roof structure intact as much as possible to avoid big hassles with licensing (I think. It seems that I remember a requirement that states a modified car must employ all the safety features that were required during the year of mfr). There is a Triumph Spitfire in the area with a blown engine that I've been looking at - that would make a great donor. The whole idea is probably way beyond me but I think it would be a blast of a project.
what about using 4 cly axles in a 3cyl car. the motor is 4 inches shorter and the axles are 4 inches shorter. That gives u 8 inches. chop top also. that would take out the passenger seat, which is the area i would cut out, put like a kframe in front and weld the body back together.
One issue with chopping the car like you want is that doing so throws all the vehicle dynamics engineering that was done out the window. What you are left with is an unpredictable vehicle, possibly dangerous. You are probably better off doing something like the half metro. That way you maintain the original wheelbase and handling characteristics (for the most part).
think about this .. make it far simpler than a total cut in half and still allows for 2 maybee 3 seat.. Tear drop it and make it 3 wheels , 2 in front and 1 in the rear.. then it could be licensed as a motor cycle , motor cycles have far less "regulations" for being legal , its basically 1 mirror, and one operable break..and signal and break lights for the most part.
Any way you do this its going top be a big project.. a extreme chop top may be the most effective easiest way to lessen your frontal area of the car.. imagine sloping back the windshield having side windows about 6" high.. that would take a huge chunk of frontal area of the car.... make a 4 seater a 2 seater where your almost reclining as you sit in it..