The other day I decided to reset the trip meter to see how many mpg I could get with the most aggressive engine off P&G possible. I was doing a bit over 60mph average on the freeway so this wasn't really shooting for
maximum fuel economy. However I was accelerating at the maximum load possible where the engine doesn't run rich, so it was essentially near minimum BSFC the whole way.
The meter recorded a bit over 16 miles for a 34.3 mile trip. I think in reality it's fair to call it 16.0 miles since the car considers rolling with the engine off but key on as 0 mpg when it's really infinite mpg. We'll call it 2.1x the displayed mpg.
Displayed mpg was...23.7. 23.7*2.1=49.8
Computer is probably optimistic, but hey, it's a lot better than 37, and the trip only took 5 minutes more than usual when cruising at 65-70.
Coming back, I forgot the numbers but remembered calculating it to be something like 48mpg in my head.