[EcoVan]

My 1998 Escort gets around 30 highway ( I just upgraded the injectors, so it may be better now), with my previous 93 Escort was approaching 50 highway My 2017 Chevy Full Size van gets around 30 to 35 highway and around 20 to 21 in the city when carrying 2500 lbs at minimum(service truck) This is the vehicle that gets the most driving.

The Jeep is a 3.7 v-6 that is now getting around 24 highway and 16 to 17 city. The only things done to the Jeep so far is a properly flowing exhaust and closing up all the gaps around the radiator in the front grill.
The v-6 Jeeps have some real potential for getting pretty good gas mileage. The engine only spins around 2100 RPM on the highway and the trans stays locked up in overdrive down to around 32 MPH. Its got enough torque to pull the Jeep up hills at 32 mph at only 1200 rpm. The Jeep is still pretty hefty at 4350lbs (4wd), but is about 350 lbs lighter than the smallest v-8 model and 800 lbs lighter than the current SRT (which is about 200 lbs heavier than the previous SRT).

StrongJeff, a big contributer to the high performance 3.7 v-6 thread on the Jeep forums , is running between 26 and 32 highway with his 2008 Jeep Grand Cherokee 2wd with no aero mods but just about any engine performance mod outside of internal changes.

Also, properly maintained, these v-6's last forever. We are at 220,000 miles and is doesn't burn a drop of oil. I understand you really have to make sure the cooling is in good shape. I did a new water pump, bigger 4.7 v-8 radiator (cheaper than the v-6 rad) and a full cooling system flush a couple years ago.

With the air dam and front belly pan and a couple more engine upgrades ( improved intake is next), I could be looking at 30 highway.