To add to this, if you look at Fuelly.com where owners hand calculate their mileage and the website averages it all together, you'll see that there's over 40,000 combined miles accounted for on the JL Wrangler EcoDiesel now, and the average MPG is 20.7.I haven't seen anything official. Kind of funny that they're taking orders for these, but haven't released all the important info. on them.
The Ram 1500 window sticker shows 29 MPG highway. I can tell you that I've never seen anything remotely close to that, even with the cruise set at 70 on open roadway.
That lines up really well with the 21 MPG I'm seeing with the Ram as well in mixed driving.
And, apparently on the 2021 model year window stickers, the MPG has been decreased, which is likely closer to average but still optimistic based upon real-world reports.