Doax's numbers sound about right.
I often have people say things to me like, "So what kind of range do you get on a charge on that thing, 100, 200 miles?"
Most people don't have a basic understanding of power, energy, and weight involved in a project like a home-built EV.
A 50 mile/55 mph is not a beginner conversion, it's a pretty solid vehicle that will take plenty of time and money to make happen. Take a look through the EV Album -
EVAlbum: Build Questions
Page through a few of the vehicles listed there. Take careful note to compare the speed and range specs to the cost of conversion. Many of the high-end vehicles are labors of love, and cost a pretty penny.
Also, just get any information on electric conversions you can - hit the library, talk to people, find your local chapter of the Electric Auto Association, and show up at a few meetings.
A CRX would be a cool EV, but I don't think it would be practical for a longer range vehicle. Might be really slick with a small, high-voltage battery pack though!
Of people I personally know, the guy with the S10 Pickup conversion has a very nice truck. Once he's totally finished with it, it should have a pretty good range. His has somewhere around 24-26 batteries in it. Keep in mind that the CHARGER for his truck cost about the same as my entire car project.
Tom's Dodge Neon conversion is going to be great when finished. It will have 300 volts of batteries in it. Basically removing the back seat and filling the car with lead. Also, his car is AC, which is more efficient, and will have regenerative brakes too.
Inexpensive AND long-range don't seem to go well together in EV's. I am exploring the possibilities of a generator trailer, or using a bio-diesel or veggie oil vehicle for the longer trips, and the EV for the shorter ones.
One car seldom does everything you want it to.
Just think how many gallons of gasoline we could save if even a small percentage of people drove an EV every other day!