Compact cars tend to have a seating capacity of four or five adults and a payload between 827 and 895 pounds.

For smaller hatchbacks, such as the Ford Fiesta, you’ll find that virtually all modern touring caravans will exceed the car’s maximum towable mass. With the Ford Focus, for instance, the maximum braked towable mass varies from 400 to 1500 kg, and for the Vauxhall Insignia, the range is between 1250 and 1800 kg.

A Ford Fiesta can tow a caravan if the latter weights 85 per cent or less of the kerbweight of the car. The first thing to determine is how much weight will be towed. Small caravans can weigh less than 750 kg, but some large ones can weigh 2500 kg, so you need a little research.

A car is deemed to be overloaded if its weight exceeds its official Gross Vehicle Weight (GVW). The same penalty applies if a car without two wing mirrors is carrying items that block the view out of the rear window.

If you’re in a collision, those boxes can fly toward you at high speeds. With safety in mind, don’t pack anything above the top of your back seat, Western State Insurance advised. If you’re tempted, just remember that you could be the cause of an accident, which could raise your auto insurance rates and hurt someone.

And if you own a convertible, experts say you shouldn’t transport anything on the roof. “The size of the car and its roof determine how much you can put on it,” says Alex Leanse, Content Marketing Coordinator for YourMechanic.com. Beyond roof real estate, you’ll also need to consider how much your cargo weighs.

The bottom line is that weight limits vary on every car. Some sports cars (which sometimes only seat two people) will have a lower weight limit, while larger SUVs and mini vans will have a much higher one. A carload of five adults would have to average 170 pounds per person to come in at an 850-pound weight limit.

Moving Day: How to Secure Furniture to the Top of a Car

1. Cover the Roof with Blankets. To prevent scratches on the car roof, lay down enough blankets on top of the roof.
2. Use Strong Rope. You need to buy strong rope before moving day.
3. Try Ratchet Straps.
4. Tie the Right Knots.

Roof-racks and boxes are a great way of carrying large or awkward items but you’ll need to stay within the maximum permitted roof load. Anything carried on the roof must be attached securely: The Highway Code simply says: “you must secure your load and it must not stick out dangerously”