Why Tesla’s electric cars have a long way to go — if their charge makes it

Having established a fast-charging foothold in California for its electric cars, Tesla Motors has brought its formula east, opening two ultrafast charging stations in December that would, in theory, allow a speedy electric-car road trip between here and Boston.

But as I discovered on a recent test drive of the company’s high-performance Model S sedan, theory can be trumped by reality, especially when Northeast temperatures plunge.