The EPA does not even produce fuel economy estimates for vehicles as large as the F-350, but data I can find gives about 13-14 mpg in real world use, perhaps about 20 mpg on the highway in ideal circumstances. Meanwhile the 2021 Outback (which is not particularly fuel efficient) is EPA rated at 26 city/33 highway, which is significantly better.

Customer reported data for current model Ford F-350 diesels shows about 12 - 13 mpg.

https://www.fuelly.com/car/ford/f-350_super_duty?engineconfi...

Subaru Outback is about 23 mpg.

https://www.fuelly.com/car/subaru/outback?engineconfig_id=86...

Of course those are self selected samples and not independent tests, but still probably close to what most drivers will see in the real world.

Which are themselves not especially fuel efficient compared to the Impreza much less a hybrid or efficient compact sedan.

I drove one for a few years… I recall 14 mpg. But it wasn’t a commuter vehicle, and I’m not an idiot burning smoke like many buyers of fancy F350s.

Usually the consumer midsize crossover nets out around 20.

…which is not remotely relevant to the actual point I was making.

Diesel is more energy dense, so better to compare it to a VW TDI of 40+ MPG. You are still hauling around all that weight. I have always wanted a VW (Rabbit) pickup.

I don’t know why there are no diesel-electric trucks. If you need torque, do what trains do.