At the urging of the government of the Japanese Prefecture of Fukushima, a development group has developed a conversion kit that removes petroleum fueled power-train in favor of an electric one. The Miata now has an electric motor and battery providing a top speed of 62 mph and 19-mile range. For a car so ideally suited to sunny day driving they also added one obvious extra feature: solar panels. Given the limited surface area of the Miata, the solar charging capability is probably limited but it's still a worthwhile effort. The kit doesn't come cheap at an estimated $21,000 which is quite a bit more than a first-gen Miata cost new, but no one said being on the bleeding edge came cheap.
[Source: PhysOrg, thanks to Domenick for the tip]