There are Diesels on the lot for a good reason - they are not popular. Where I live, diesel fuel is about 25% more expensive than regular gas, so the economics do not work to purchase a diesel. With my 1.5L, I can get 33-35 MPG highway, and average about 31 MPG on my typical driving, about 75% highway. Plus, there seems to many more issues with the diesels than the gas engines.
Just my $0.02
2018 Equinox LT1 1.5 L 4 cyl, AWD, S/R Cajun Red Tintcoat/Black
2010 Equinox LTZ 2.4 L 4 cyl, FWD, S/R Cardinal Red/Black