"How to Build a Sports Car for 250 Pounds -- and Race It" by Ron Champion
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Engineer
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Young and broke-ish
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MR2 Spyder ownership that turned me on to lightweight sports cars
Fast forward to 2008, I actually have some money to spend on such a thing (since 250 pounds is pretty much a joke), although less time and space than I had in 2002 when I bought "The Book." I bought an unfinished project and am now in the process of not finishing it myself
It's at least $8,000 cheaper than the Prius, though, and is gasoline-only. That's a plus for some people, who are afraid of long-term battery/electronics issues. It's also much easier to park in congested cities. The Smart is definitely a city car. Aerodynamics and lack of power cause it to suffer a bit on the highway.
True, the R1's are quite small. Most of us are shying away from the motorcycle shocks now, however, because it's proven nearly impossible to get a good balance of suspension travel and spring rate/damping. By and large, locosters are just ponying up for proper custom automotive coil-over units like the Proma Star QA1 and Strange Engineering shocks.
It's all in the setup. Given similar HP and similar suspension setup/development, I'd say they're about equal. Just pick the one you like (and can afford ) and get it dialed in properly.