Those who want to tow heavy trailers will find few suitable companions among the e-cars and plug-in hybrids – for technical reasons. There are a few bright spots like the Tesla Model Y, but there are also negative examples like the VW ID.3.
There was a time when the BMW 530e, the plug-in hybrid version of the series, was only allowed to tow 750 kilograms. A measly towing capacity for an upper mid-range model that can tow trailers weighing up to 2,000 kilograms with a pure combustion engine. But now the 530e and its plug-in hybrid brethren are finally an alternative for drivers who frequently travel with trailers: BMW has raised the towing capacity to 1,700 kilograms – enough for most caravans or horse trailers. The all-wheel-drive 530e and 545e xDrive can even tow up to 2,000 kilograms.
BMW has increased the towing capacities of its 5 Series-based plug-in hybrid models
The previously very low towing capacity had nothing at all to do with a lack of engine power. According to BMW, the nature of the rear carrier structure limited the towing capacity. Strengthening it is said to have necessitated extensive conversion work, after all this is where the lithium-ion battery is located. The weight of the battery sets further limits, and this is where the issue of axle load distribution comes in. But the Munich-based company seems to have mastered these challenges in the meantime.
Plug-in mid-sizers with a towing capacity of around 2 tons
As a result, the partially electrified 5 Series has now caught up with the plug-in competition. Both the hybrid E-Class 300 e (gasoline) and 300 de (diesel) and the Volvo V90 T8 Twin Engine take up to 2,100 kilograms on the hook. The VW Passat GTE has a maximum of 1,900 kilograms, and the Audi A7 55 TFSI e has a towing capacity (braked) of 2,000 kilograms. Here it comes down to little things – such as the clutch in the transmission. Mercedes, for example, has been using a nine-speed automatic with torque converter, torque converter lock-up clutch and disconnect clutch in its plug-in e-classes for some time, which is supposed to promote a high towing capacity. Wet clutches, as used primarily by the competition, are said to have disadvantages in this respect.
If you dig through the data, it becomes clear that anyone who wants to buy a car with an electrified powertrain and also tow a trailer regularly will still find a very limited range. This does not apply to the mild hybrids with 48-volt systems that are currently flooding the market; their towing capacity can generally keep up with that of pure combustion engine models. But models with reasonable towing characteristics are in short supply, especially among the full-time Stromers.
The battery as a hindrance to towing capacity
There is a central technical reason for this: the battery. In terms of the energy it can provide, the battery is currently very large and expensive. That’s why it has to be trimmed first and foremost for efficient power consumption. This can be estimated quite concretely if only the mass of the car plus crew and luggage has to be included in the calculation. However, a heavy load on the trailer hitch is an energy-consuming black box that is difficult to estimate how it will affect the energy consumption of an electric car. So manufacturers minimize the risk by minimizing the towing load.