My most recent vehicle purchase is not a Vanagon. But a Jaguar X-Type
(small 4 wheel drive sedan). I got it as I wanted a winter vehicle
OTHER than my Vanagons, and I wanted something that got (relatively)
good fuel economy.

So it is interesting (to me) to compare engine/transmission and fuel
economy between it and my "normal" Vanagons.

Vehicle   Jaguar X-type    Vanagon Syncro     Vanagon Syncro Camper
Engine        3.0 V6           3.3 H6             3.3 H6
weight        3428 lbs        3650 lbs           4000 lbs
HP             231             240                240
MPG          18-30mpg         16-17 mpg          15-17 mpg
L              n/a             6.03               6.03
1st           3.42             3.78               3.78
2nd           2.14             2.06               2.06
3rd           1.45             1.23               1.08
4th           1.03             0.86               0.70
5th           0.77              n/a                n/a
Final Drive   3.80             5.43               5.43
Tire size   225/45R17       225/70R15          215/75R16

MPG figure is real world experience GPS corrected for tire size
differences.

Tire size on the vanagon doesn't seem to make any difference towards
fuel economy (from using 205/65R15 tires or 215/75R16)

On the Jag, the gearing is oriented towards sporty. If I don't shift
extremely early the mpg figure drops dramatically. Early shifting is
around 2800 rpm (at most). On the Vanagons, I find that if I shift at
less than 4000 rpms, the engine tends to accelerate VERY slowly (On
the Westy, the big jump between 2nd and 3rd really means I wind up 2nd
pretty decently.)

In reviewing all the specs, it occurs to me that while the
aerodynamics make some difference as to the fuel economy, especially
above 50 mph, it is possible that the final drive ratio is the big
difference.

I'll have to do a lot more experimenting with driving habits in my
passenger syncro to see if I can't make a significant impact on my
fuel economy.