Wifey had to drive to her mom's - a 420 mile round trip excluding local driving - so she get's "Zephy" and I get "Dury" the Durango for my on-call weekend.
She called from the highway to report 44mpg
Wishing I'd dragged the kids out with her for a clinic last night...
On the plus side, if she had taken the Durango she'd be pulling about 15-17mpg on the same route by my reckoning - the very best I've ever got was 19mpg on a highway run.
I also plugged in the OBD to the Durango and found a high-current alert on one of the O2 sensors...

but no engine-light. Not able to get FE calculated with the kit/software on that car yet. Maybe a project for the weekend home alone.