Diesel SUV for 23' or 25' FC

Hi friends...a newbie, working on the tow vehicle issue before I purchase my AS. Looking at the Mercedes Benz GL series, Volkswagen, or? It looks like the top weight for any of these is around #7000. to #8000.# Are the earlier Flying Clouds lighter than the new ones? Any thoughts on this would be great. Don't want a truck as it won't fit my current lifestyle. Initially, it looks like diesel is the way to go for mileage and engine wear. Do the luxury SUV's have the proper necessities to tow efficiently? Not even sure what ??? to ask. Thanks in advance. This is a great forum and I have learned so much from all of you!