How about a low power electric car that get on a PRT line AND get charged while on it? It would have to be compatible, of course.
What is needed is the creation of standards for both hardware and software. Such standards may make it more difficult for one company to own an entire market, but the size of the market will grow much faster if anybody can build a PRT line or build cars for them to an open standard.
Such standards should also encompass automated inspections of both cars and lines by each other (cars would inspect lines and lines could inspect cars) for compliance to the standards.
I think the latter notion actually has some merit. While letting electric cars in is not very feasible, having a standard would certainly help comfort those who would pay for such a system.
Once purchasers see inertia building with several companies building cars and/or lines to a standard, the investment starts to look predictable and that is certainly needed here.
An open standard would encourage companies to get into the business as well.