In my little rig: I like the power output of the V-10.
It climbs the steepest hills around here easily (no small feat!), and the fuel mileage is actually not that bad at all. (Just under 10 mpg.)
This of course doesn't mean that they shouldn't try to come up with a better engine. I have no doubt that the larger gas-powered Class As could use a hand.
Perhaps the manufacturers should just look to expanding the use of diesel engines a little bit????