Is the MPG of our Nomads really all that bad??

Over the years I have enjoyed several different brands and types of motorcycles. I like to keep tract of my fuel mileage and tune for good fuel mileage as well as performance. Listed here are some of the motorcycles I have owned and the average MPG they obtained.
1972 Honda CB 350 twin 50 MPG
1970 Harley Sprint SS 350 thumper 55 MPG
1982 Suzuki GN 400 thumper 55-60 MPG
1968 BSA THUNDERBOLT single carb. 650cc British twin 50 MPG
1971 BMW 750 cc German opposed twin 50 MPG
1978 Moto Guzzi T3 Italian V-Twin 850 cc 42 MPG
1982 Yamaha Maxim 750 cc transverse 4 cyl 45 MPG
1986 Suzuki 550ES 564cc transverse 4 cyl 46 MPG
1999 GL SE Goldwing 1500 cc opposed 6 cyl 40MPG (if not ridden hard)
2006 Suzuki C-50 800 cc V-Twin 52 MPG
2007 Kawasaki Nomad 1600 cc V-Twin 40 MPG

From talking to owners and reading the forums on other current large displacement bikes many report about 35 MPG

Does not seem to me that our Nomads are doing all that poorly for 1600cc 800 pound motorcycles . My 40 MPG average improves to about 43- 45 MPG on road trips.

The big difference I have noticed over the years is that automobile fuel mileage has greatly improved making our motorcycles seem inefficient by compassion. My daughters Honda Civic gets about 32 MPG.
I remember back in the 60's Full dress Harley 74 cu in got about 40 MPG and the then hot Sportsters got about 30 MPG

Most of my bikes dropped in fuel mileage when ridden in cold weather using winter blended gas by approx. 5%-10%