we had a 2.0dti Zafira and our limit was 1050kg but this was because the gearbox coolant wasn't up to the job (or so we were told). It towed our 2 berth van lovely. We also had a 1.8 petrol Vectra and we ended up trading it in because it was too sluggish when towing, was having to drop down to really low gears to get up hills etc and also used to burn the clutch every time I reversed the van, best move we made at the time
------------- -x- Diane -x-
May 13 - Cala Gogo, St Cyprien (didn't go, hubby too ill to travel)
May 14 Ranc Davaine
August 14 Les Sablons
August 13 - Camping Playa Brava, Pals
Our Zafira 1.9 TDCi struggled to pull our old caravan at 1150kg. It was fine on the flat but you had to drop it down on the hills. Saying that we got round France with it fine.
I think your 1.8 may struggle going beyond 1150kg. My best advice would be to keep it to this level or change car. We ended up changing our second car to a land rover discovery3 as we wanted a bigger newer caravan. Best thing we ever did. The Disco tows a 1350 kg, carries 4 bikes, 2 adults, 3 kids, and a kayak on the roof, and it doesn't even seem to notice the weight! Returns better mpg than the Zafira under load too!