EV conversions are a neat and a hardware hacker's dream, or perhaps nemesis.
http://www.nedra.com/pg_white_zombie.html is the amateur record holder for an EV conversion factory vehicle, a 1972 Datsun 1200. While racing fuel dragsters can beat 11.446 @ 114.08 mph, a gasoline 1972 Datsun [FONT=Verdana, Arial, Helvetica, sans-serif][/FONT]1200 sedan typically does not!
**broken link removed** shows a lot of what's possible.
They can be fast accelerators, but typically have a low top speed. They have outrageous low-end torque whereas gas engines have low output at low rpms.
A 100mph range would be really really high without a custom-designed ultralight, low-drag body. 40-50mile range is more realistic for a common sedan and there's some caveats to that. One being that running your batts down all the way will shorten their lives, so don't plan on putting it into service for a 40 mile commute. Cold temps lower the capacity, as does age.
Only a few battery types actually work "well" in an EV at all.
Unfortunately the price of lead, as well as nickel for NiMH batts, has skyrocketed in recent years alongside gas prices. Batts are much more expensive.
The batts do have a finite life as well, very short if abused, but lead-acid is only capable of a few hundred cycles even when treated ideally. It's difficult to compare cost-effectiveness here without knowledge of the actual cycle life expectancy. Mfg figures are typically rather "optimistic". But, well, 300 cycles (that might be very optimistic for EV duty) and it's equivalent to say 1.5 gal of fuel per charge @ $3.75/gal = $1687 in gas. Unfortunately batts can run much more than that, but the cost of electricity isn't that much. Motor, controller, modifications can be many thousands of dollars. Don't do it for the money. It makes... well,
some sort of statement, and it's just plain cool to have a car running on batts.
Solar panels are typically a bust. A "normal" vehicle run as an EV needs about 300 watt-hours/mi to drive around if well designed. So 50W of solar panels- which is a lot- could regenerate about a mile of range during the workday if left in the parking out without any shade, in lower latitudes, during the summer-ish part of the year. Unless it's a wild conformal panel design, the extra drag of a panel will cost far more than 1 mile of range.
Electricity is cheap. At 10 cents/kwh that's a bit over 3 cents/mi which is like having $1/gal gas again. Getting 28 mpg at $3.75/gal is 13.3 cents/mi.