Why diesel cars make great load carriers

If you have ever towed a trailer, you will know why low-end torque is vital. In this article we explain what torque is, how diesel provides it, and why it is so important.

The diesel engine remains the most popular choice for those towing and carrying loads. This is due not only to a diesel engine’s high levels of fuel economy, but also its ability to deliver greater torque at low engine speeds. Whether it is towing caravans, trailers or boats, it is hard to imagine anything better suited to the task than a diesel engine.


What do drivers tow and with what?

Towable objects come in all shapes and sizes – from a simple trailer or caravan, to large commercial units carrying items such as heavy goods and livestock. Whatever object is being towed, it causes additional weight and drag for the load carrier, which needs more engine power to move both vehicle and object forward, especially when driving uphill.

The higher cylinder pressure of a diesel engine achieves good fuel economy, making it the most popular choice for many commercial uses, such as vans, buses and heavy goods vehicles (HGVs).

This higher cylinder pressure also makes diesel engines capable of producing greater power at lower speeds than their petrol equivalent. This offers the “low-end torque” and more relaxed driving experience sought by load carriers.

When towing, a diesel engine does the equivalent of someone carrying five bricks at a time, rather than moving each brick individually, and while a diesel engine does no more and no less work than a petrol engine, it does the same job more efficiently.

Car towing caravan - why diesels make great load carriers

What’s the difference between torque and horse power?

Torque and horsepower are related aspects of an engine’s output, but they are not the same thing. Horsepower determines how fast you can travel over a given distance, but that same power can be produced using either a high torque, where the engine turns slowly, or a low torque, where the engine turns quickly.

Torque is just a turning force – the same as you would apply to a screwdriver. In a car, torque describes the output from the engine, which is then transmitted via the gearbox to the wheels that drive the vehicle along. The torque produced by a combustion engine depends upon both the pressure in the cylinders and the size of the pistons.

As a general rule, larger engines produce greater torque. However, manufacturers are able to produce higher torque, and so higher horsepower, from smaller engines, using turbochargers and superchargers. These devices force more air into the cylinders, allowing more fuel to combust and resulting in higher cylinder pressures.

An engine with high torque enables you to move a load without constant recourse to high engine speeds and low gears. It is about having the same power available, but at lower engine speeds, making it particularly useful for load carriers towing heavy objects.

Diesel remains the preferred choice for towing and load carrying

According to estimates from the UK National Caravan Council, out of 550,000 touring caravans, 365,000 caravan holiday homes and 225,000 motor homes in the UK, the majority rely on diesel-powered vehicles for their towing needs. Leisure tourists such as these often choose diesel to minimise the time spent worrying about whether or not they will make it to the top of a hilly road, or whether they can safely overtake a slower vehicle.

Whether it is towing caravans, trailers, or boats, it is hard to imagine anything better suited to the task than a diesel engine.

More than 90% of light commercial vehicles registered in the EU are powered by diesel engines, according to the industry figures. As such, the diesel engine plays a crucial role in both minimising costs and reducing CO2 emissions in the transport economy.