GM’s stock is taking a beating! It’s plummeted 34 percent since the IPO. Warren Buffet’s baby, Chinese automaker BYD, is also taking it on the chin following a disappointing profits report. Saab is sinking . . . fast. Its financial situation looks grimmer by the minute as debt collectors come a-knocking. All that and more, plus another power-to-weight comparison, this time with V-8 ponycars.