Mileage Older style MH vs Current Style

[Craig36]

I was talking to a fellow RVer on the ham radio the other night, and we were discussing mileage on the older (pre basement) motorhomes vs todays.

Back in 1982 I had a new 34 foot Pace Arrow gasser that averaged 10 MPG, and came close to 12 mpg, if you drove 55 mpg on flat terrain. The diesel guys did a couple of MPG better. Back then pointed noses and streamlining was better than we see today.

I wonder why we aren't seeing progress in designing for minimal wind resistance? (Semis have) Further, my current DP gets worse mileage than my last gasser of about the same size. Yes, it weighs 10K lbs more, but once you get a diesel rolling, one would expect to get better mileage on average.

Am I remembering things wrong?

[mat]

my old motor home (Large Marge)was only 26' with a 440 mopar engine. aerodynamic as a brick and was only good for 6-8 mpg. the newer coach is also good for 6-8, but, it has a much higher GVW and 3 slides and is 10' longer, and always pulling some kind of trailer. So I guess in the long run, we've gained a little, even though the mpg remains the same.