PORSCHE should be applauded for developing a petrol-electric hybrid version of its popular Cayenne, but is it really in the best interest of the sports-car brand? With formidable performance, diesel-like economy and relatively low emissions, this is the next step up for luxury SUV buyers who have outgrown a Lexus RX450h. However, there are some serious – and quite unexpected – drawbacks, enough to leave us wondering if buyers should save $55,000 and go for the more humble Cayenne Diesel instead.