Investing in electric vehicle makers can have massive upside, but not all EV investments are created equal.While the U.S. electric vehicle (EV) market has accelerated more slowly off the line than predicted, the future is still almost certainly headed in that direction. Finding the right EV makers and holding them long term could prove lucrative for investors, but picking the right EV maker is easier said than done. We'll take a quick look at why there might be an upcoming buying opportunity for savvy inves ...