Turns out the SUV isn’t the problem. It’s large trucks moving goods thousands of miles, getting three to five miles per gallon and clogging up our highways.
It'd be nice if he'd do a little research. I'm disappointed in my new truck (2006 Freightliner FLC 120 w/ 445 14L Detroit) , it only gets 7.5 MPG. On the same run a 2000 Freightliner FLC 112 w/ 370 11L Cummins got 8.5, and a 2000 Volvo VL w/ 270 11L got 9.2. I run light loads but have to run about 16% idle (liftgate) and hilly terrain.
Back in the bad old days before electronic engine controls 3-5 MPG was common, but anything in the last 10 years spec'd and driven properly will beat that. Cats run in the high 5s to low 6s, Cummins 6s to high 7s, and Detroits 6s to low 8s. If speeds are lowered those numbers will improve.
And as to which type of vehicle burns the most fuel a picture (or in this case a graph) is worth a thousand words (keep in mind that Distillates used in transportation encompasses diesel for trains as well as trucks [and diesel pickups and passenger vehicles, but those are a small share)
Graphic from EIA report on demand