A diesel engine , by it's very nature and owing to the use of diesel fuel, is much more suited to staying idle without being used than a petrol. So, whatever the people are saying makes no sense. Today's modern diesels are even better than some petrols in matters of technology. Your needs as of now point to the Punto. I'm 6 feet myself and find myself comfortable in the driver seats of both the Linea and the Punto. As for the fuel efficiency, have a look at the fuel efficiency thread on TFI. You'll get to know the exact and real world figures. Cheers.