The NEW Volvo D5 turbocharged diesel engine = 60 Miles Per Gallon

For some reason many people still look down upon the diesel engine, citing billowing clouds of black smoke as their reason. However, today's diesels are much cleaner and offer a great amount of efficiency when used properly. Volvo is out to make this message even clearer with the introduction of their newest lineup of diesel engines. 

Source: http://inventorspot.com/articles/volvos_new_diesel_promises_be_cleaner_and_more_efficient_38143