They may be slightly safer for the occupants of the car, but the height factor kills 30% more pedestrians and in actual fact accident fatalities are up as a result of SUVs as they incite risk-taking behaviour and roll over in accidents much more readliy. Additionally, they only have to accede to truck safety regulations with are less stringent than those for cars. I can point you to loads of papers and articles on this. They purely are a marketing ploy as they are more profitable vehicles for the manufacturers. BTW those MPG ratings are shit by today's standards; most cars do 45MPG+.