Company car drivers who use SUVs to tow trailers, machinery or horse boxes could have to undergo compulsory training and even sit a new driving test.

The third Directive on European Driving Licences, aimed at harmonising driving licences across the EU, must be transposed into UK law by January 2011, and must come into effect within the following 24 months.

Part of the regulation addresses the power-weight ratio of vehicles. It says that for a combination of vehicle and trailer that exceeds 3,500kg in total, “a training, a test or both a training and a test will be imposed”.

Many large SUVs already exceed 3,000kg on their own.

While the directive is clear that an additional test or training will be required, the Driver and Vehicle Licensing Agency (DVLA) remains undecided about how it will be implemented.

“We are currently conducting informal discussions with external stakeholders who are likely to be affected and we will also carry out formal public consultation,” said a DVLA spokesman.