Dyson will fight an EU court battle over Brussels’ energy efficiency rules later this month, arguing the current regime allows rival vacuum cleaner makers to mislead consumers.

The British engineering group, best known for its bagless vacuum cleaners, believes the existing EU rules puts the company at an unfair disadvantage, since energy labels does not take into account whether ­rivals’ products are tested for energy efficiency with a new or used bag.

It argues that unlike its own products, bag-based vacuum cleaners consume much more power outside of laboratory conditions, but are allowed to provide “Class A” energy ratings that do not reflect how they perform in the home.

On October 26, Dyson will go to the ­European Court of Justice (ECJ) in a case against Bosch Siemens. It claims the company is misleading customers by not specifying that energy efficiency tests are done in laboratory conditions.

Dyson says the vacuum cleaners ­made by Bosch and Siemens consume significantly more power under normal use, once dust is in the bag, than under the conditions used to test its energy efficiency. Bosch and Siemens parent company BSH Home Appliances has countersued on defamation grounds.

Dyson founder Sir James Dyson credit: Heathcliff O'Malley/Telegraph

The case was originally brought in Belgium but escalated to the European Court last year. Arguments will be heard later this month, although a decision is not expected for some time.

Dyson, which says it has invested £350m in researching and developing digital motors, is fighting a separate case in Europe claiming that the energy tests themselves are unfair and should be changed. In 2015 the EU General Court ­dismissed its bid to change the tests, but Dyson was given a lifeline in May when it successfully appealed against the decision.

The ECJ ordered the lower court to take into account a “deeper assessment of the evidence”. At the time Dyson called it a “rare and historic win for consumers”.

Last week, Dyson replaced its chief executive, Max Conze, with Jim Rowan, its chief operating officer. The move comes at a critical juncture for the company, which has just announced plans to build an electric car in 2020.

Sir James Dyson, the company’s founder, said last month he would ­invest £2bn in a “radical” new car ­design that is being built from scratch. As part of the plans, the company will open a new testing facility in the UK on a former RAF base in Wiltshire.

Dyson did not comment while BSH could not be reached for comment.