Hello
Thanks for all about good tips and comments. Everything went well (first 160 km). Omega really seems to be good for this purpose, too. My earlier short experience 15 years ago was with 950 kg Small Solifer Caravan and Opel Vectra 1,8, those front wheel drive constructions. This is really something else.
1. Cruise behaves with Van quite in an "angry" way. It tries to accelerate quicker than I would do manually, decided to use cruise only for keeping the manually accelerated speed.
2. As discussed max speed here is 80km/h=50miles/h which means about 2000 rpm if torque converter locked. With cruise control it really last long time to get TC locked. I accelerate manually to slightly higher speed than needed and then take my foot away from acc. pedal, wait the lock up and press cruise on. That seems to work perfectly in down-hill and "flat" but when climbing to hill AR-25 shifts down perhaps to gear three to get about 3500 rpm. Guess Y26SE have quite low torque in 2000rpm.
3. Fuel consumption Increased about 50%. This Van is quite wide 234cm = >92 inches and front wall and forehead are quite "vertical" so has not that much angle than Vans with better aerodynamics. So maybe normal.
Seems about right ...
1) I very rarely use cruise when towing as it is a bit binary, either off or on the throttle, I find "normal" driving where you can "feather" the throttle far more comfortable, and it appears more fuel efficient. I guess continually trying to accelerate the best part of 3.3 Tonnes at a high rate will burn fuel !!
2) About the same as I do, accelerate to just above what you want then trickle back and it locks up nicely. On hills "feather" the speed back a tad and it stops the kickdown.
3) 50% is VERY high, I drop from around 23 mpg solo to about 17 mpg towing (on gas [LPG] its from around 21 mpg to around 15 mpg but that's to be expected). 2.34 width is not unusual ... mine is 2.32, but being just 2 years old is quite "aerodynamic" as designs have improved.
UK max speed is 50 mph on single carriageway, 60 mph on dual carriageways so not a huge difference. I wonder if your increased consumption is simply driving technique ?? When towing take everything much more gently, both acceleration and braking and it makes a huge difference to consumption. Also, tyre pressures and brakes on the 'van are important .. if the brakes are binding, even a little, its a lot of extra energy required. easiest way to check is to drive 2-3 miles with minimum (preferably "no") braking, "drift" to a halt - safely - and then feel the 'van hubs.... should be pretty cold, if warm the brakes are dragging.