Gas vs Diesel (I've read the FAQs!!)

ZagiFlyer wrote:
Hello to All,

We *still* have the Thor Jazz in my sig, and it's still a going concern, but the wife is up for a change and "we" are wondering if a Class A would fit the bill. Many of our trips are long-range and we'd like to be comfortable driving cross-country -- my daughter has informed me that the back seat of an extended cab is not making her back happy on 6, 8, 12 hour drives.

Keeping in mind that we're coming from a 5th-wheel towed by a 6.0L gasser, my wife is under the impression that a DP will fly up the Grapevine (6% grade) at 50-60 mph. Is this true? I wouldn't expect it, since the HP/torque required to move 26,000 lb up a 6% grade at 50 mph would be enormous.

I've read the FAQs and searched the forums, but I didn't find anything specific enough so here is my question:

Thinking along lines of the Grapevine or other steep/long grades:

• At what speed are you 36-40 ft. DPs getting up steeper grades
• At what speeds are you 36 ft. gas Class A's getting up steeper grades?

For comparison, my rig gets us up the Grapevine at about 35 mph, but it's struggling mightily at 4400 RPM.

I need to set her expectations realistically if I am to acquire any semblance of domestic tranquility when we upgrade.

Thanks!