You'll have to be very careful shifting heavy weights with an estate car as it won't take much to overload the suspension and increase wear on the brakes. If you're carrying the weight for work, it's also worth noting you'll need specialist business insurance. I'd recommend a van-based people carrier (vans.honestjohn.co.uk/van-top-10s/top-10-van-based.../) like the Citroen Berlingo or Vauxhall Combo. To work out whether a vehicle can carry heavy loads, you'll need to find out its gross vehicle weight (GVW). This is the maximum weight a car or van can legally operate at including fuel, passengers, luggage etc. This is usually found inside the door or in the handbook.