BTW a diesel motor in a 39' MH will deliver at least 30% better fuel mileage than the same size 39' with a V-10. once again not putting down the V-10 it is right sized for the smaller class A's.
This simply is not true for current diesel and gas offerings. 10% maybe. Then again the fuel is 10 to 15% more expensive so its a wash on fuel cost.
39ft with a trailer is at the limits of what available gas engines can do. Diesels handle that and larger with ease. Smaller than that and the advantage goes further and further to the gas side. Its in that range where other factors like preference and cost vs percieved benifit are a bit more fuzzy.
Since when did we RV for cost savings?
2008 Damon 3575 (38ft, forward kitchen)on Ford 22k chassis
Its all down to gearing and what the driver is willing to deal with. Maybe they just tug along at 35-45 on a climb keeping the gasser in a power band, maybe it has the power AND gearing to continue at 55 up most reasonable grades but at the cost of fuel and high RPM. When it comes to stopping distanances an electric brake controller for the trailer will significantly cut down stopping distance just like a toad with a braking system so thats not much of an issue. While I personally own a pusher and yes it has great power and brakes, I still use a brake controller for the open and enclosed trailers I tow from time to time. Since I do not tow my car 4 down (either a dolly or the open trailer) I do not have a braking system for that.
2006 Ford F350 6.0
2014 Primetime Sanibel 3600
Enough other vehicles to not bother listing.