The idea of producing large, luxury-vehicle hybrids is turning into a "what were they thinking?" exercise in futility, USA Today reports. General Motors is discontinuing hybrid versions of the Cadillac Escalade, Chevrolet Tahoe and GMC Yukon SUVs, while Mercedes-Benz and Toyota's Lexus division are doing the same with their S-Class hybrid and LS hybrid sedans, respectively. The culprit? Big price increases for fuel economy improvements that border on the unimpressive.