Weight a car can carry...

[Plocket]

How many breeze blocks can be carried in the boot of a standard estate car, without causing any damage to the vehicle?

[TWR]

When the top of the tyre catches the inner wheel arch, you have enough. Dont forget the first pot hole you may need to replace the rear Suspension cracked springs.

[Graham-W]

It's important that you don't exceed the Maximum Authorised Mass (MAM)/Maximum Permitted Weight (MPW) for the car. You can find the figure for your car on the 'VIN plate' under the bonnet or in the handbook. Remember to include all weights when working it out, including the driver, spare wheel, fuel etc.
You may have to adjust the tyre pressures for the additional load.

[TWR]

Why not get a van? by doing that you will cause no damage to your car.