fuel consumption when towing
 

what effects on fuel consumtion would you expect towing to do ?
examples - small trailer, little dinghy - Id expect very little worsening
largeish trailer, say 8x4 open box, 20% ?
small caravan - 40% ?

all assuming keeping within speed limits, not hooning around at 90

This depends a lot on what you are towing with, as petrol, diesel, engine size, torque and BHP are all in the equation.
As for me, Towing the same caravan had greater effect on my 850 2.0L petrol/LPG than on my XC90 2.4 D5 and this is mainly to do with the max torque on the 850 was around 3-3.5K rpm as with the XC90 is around 2-2.5K rpm.

My V70 2.4 N/A petrol 140bhp normally averages about 30-32MPG
With the twin axle 1100 kg unladen (probably closer 1300kg all up) caravan on the back it drops between 22-24MPG.
The only issue is that even on the motorway at 50-55MPH you struggle to get it in to fifth gear as the ratio is too high and the car is very high geared on fifth gear (like overdrive).

SC

It all depends on what you are towing, what it weighs, how big it is and the type of road you are driving on. as well as what car you are driving.
I have found that the big Volvo's give very good mileage when towing compared to that they give when being driven solo.
Last week, I took a large 4 wheel Ifor Williams car transporter down to Nottinghamshire, with my XC90, and returned with a car on it. The average for the journey was 32 mpg and it was the same going down empty as coming back with the car. This is not much less than I would expect doing the journey without the trailer.
When towing our caravan, we normally get about 26 - 28 mpg, which is about 20% below normal mileage.
Our last car, an XC70, would often do well over 30 mpg with the caravan, while a friend with a Honda CRV, doing the same journey would get only 22.
I was talking to someone yesterday who has a Ford Focus diesel, and he said that he gets about 28 mpg, towing an old and quite light 2 berth caravan, which is no more than we get with our much bigger car and heavier 4 berth 'van; in his case, he is only getting around 50% of his normal mpg.

It seems that big torquey engines are best for towing, and high revving jap buzz-boxes the worst. No wonder diesel volvos are so popular amongst caravanners

My van weighs about 1100kg fully laden and this last week we took it to Peterborough and back (360 mile round trip) and the V70 averaged about 32mpg. Solo on the same trip and ever so slightly faster than one should drive it will do 46mpg no problem.

Hope this helps.

I haven't towed my caravan very many miles (probably around 250 this year) but the one thing that I did notice is that my fuel economy improved significantly after the first tow - it was almost as though the additional load the engine was put under did it some good. My fuel consumption is now about 5mpg better than it was before first towing with the car.

odd, unles it needed an Italian tune-up: a good hard run to clear out soot and crap

just bought a v70 2.5 diesel,using cruise on a 250 mile round trip i achieved 39 mpg as compared to my previous 2.0 litre petrol 850 which if i was lucky i got 22mpg..this is towing a smallish caravan weighing about 1 tonne..well pleased

can confirm after 2 decent trips, that I get so far a consistent 22mpg towing.

Not bad I guess for a XC60 D5 Geartronic 230ps, 2 adults, 3 kids, with 1750kg of caravan on the back....