The 2010 Porsche Cayenne is an SUV for those who would rather be driving a sports car. At around $45,000, the Cayenne's base price may seem like a steal for the Porsche name -- but it can skyrocket to more than $100,000 depending on trim. Take note, however -- both the Touareg and Cayenne's base 14/20 mpg fuel economy ratings are among the worst in their class. Of course, the M-Class' most