The WDW Speedway did test an electric car around four-five years ago. Money was the factor, no Disney property appropriate to foot the bill or no sponsorship.
It's cool that it's one of the few Bob Gurr designed ride vehicles still in use at Magic Kingdom, but I think by this point even he would say there's better alternatives than using combustion engines.
The ones at HKDL are really smart, they have a proximity sensor and will disable the vehicle if it approaches the rear of another. Track design is more at home with Autopia in California - compact and detailed.
I think the disdane for our version comes from the fact that it hasn't seen a major change since it opened. Sure there have been minor modifications to the track and very slight thematic changes after the 1994 land refresh. Trackside it's just very sparse. There's no charm to it. No thought to the landscaping at all.