Towing capacities

You are quite right. But the companies policy is that the car has to meet certain criteria. 119co2 emissions or below being one of them, or they won’t pay the allowance, or business mileage.  We have to submit the V5. These are business need cars, not perk cars.  Harsh sounding I know, and frustrating 

Let the company supply a  Leaf then & then buy a car capable of towing your caravan 😉

I wish I had the budget to do that 

Very true, some seem to think every one has enough vehicles to cater for what ever scenario 

You don't need to spend a fortune on a large tow car. In general, people don't want big gas guzzlers so they tend to be cheaper. There are actually 4 cars in our house between the 2 of us, but their total value is less than many Astra/Focus sized cars are to buy new.

Anyway, I'd be bu66ered if I let my employer dictate what car I'm allowed to buy when they have no financial input (other than paying me at the end of the week/month )

For nearly 14 years I towed with a VW Touran 1.9 TDI 105PS. with manual box.    Our caravans were a Coachman 460/2 with a MPTLM of 1436 kg and our current Swift Challenger with a MTPLM of 1420 kg.  The car's maximum towing weight was 1500 kg, so I always towed near to the maximum permissible. There are only the two of us and, although the car was well loaded, it was by no means sluggish and returned 28 to 32 mpg when towing.  Obviously it behaved well, otherwise it would have been passed on well before the 14 years.

To suit our purposes, I have now changed to a VW Caravelle 2.0 TDI 150PS, with automatic box.  The main reason for this vehicle was its suitability for leisure outings as a day van, and the ability to keep the caravan in habitation readiness for short stop overs by loading all the lumber in the car.  Early indications are that mpg when towing is not much less, but driving solo is around 8-10 mpg less than the Touran.

As I understand it, the 1800kg is the maximum weight that the vehicle can restart on  a 12% gradient when towing 1800 kg. The figure has nothing to do with stability while towing. Until there is a problem, it is unlikely that you will know whether the combination is safe. I have seen 300 series Discoverys pulled off the road due to a sudden tyre failure, also12% is not much of a gradient. I would recommend (50 years + towing) keeping to the 85% rule. Bear in mind that caravan payloads are 'miniscule' when you consider the weight of movers and batteries, so it is difficult to keep to the stated MPLW. My current van (after consideration of movers/gas etc) leaves just 22kg for the personal effects/ food equipment etc / per berth ie what you are allowed to for ;hold luggage per person when flying. 

I would happily tow around 1500kg with your car.

Towed our twin axle caravan with our Volvo V70 with no trouble at all.

What you are over looking is the weight of the car. You quote kerb weight, but when will you have a fully loaded caravan, and an empty car? Load the car up and the % goes down. I have often towed a car transporter trailer in excess of 100% kerb weight in a Discovery 3. With just me in it, and that was a huge box like a caravan, no problem at all, but I have driven nearly everything over the years from motorbikes to coaches to low loaders.

Twin axle caravans and trailers will always be more stable than a single axle, and you will find out why when you try to move it by hand on to a pitch, but, they still need to be loaded properly and have the correct nose weight or it will end very badly.

Not so, DS3. The kerb weight will always be the kerb weight. Loading the car will not alter that or the % but by loading the car and towing a heavy van you could be in danger of exceeding the gross train weight. 

The scenario you quote is quite different as the Disco is well capable of towing more than it’s kerb weight and, providing the GTW and the vehicle’s max allowable towing weight aren’t exceeded, there shouldn’t be a problem. However, someone towing a caravan with the average family car is advised to consider the 85% of kerbweight recommendation. Overloading the car will not increase kerbweight but doing so and towing in excess of 85% could be a recipe for disaster.