Sir James Dyson, the billionaire inventor and Brexit backer, has unveiled expansion plans to accommodate more than 2,000 workers at his Wiltshire research facility, more than doubling capacity for electric-vehicle testing.

Coming despite severe warnings over lost jobs and investment from no-deal Brexit, his technology company is spending about £200m to expand the testing facility on a former second world war airfield at Hullavington, near Malmesbury in the west of England.

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The investment comes a year after Dyson announced plans to create an electric vehicle to propel his high-tech household goods company to become a rival to Tesla, the carmaker started by the US billionaire Elon Musk.

The British engineering company is developing a car that is due to be ready for road testing in 2020, with the first deliveries coming a year later.

Dyson’s expansion plans for the research and development site, which is already home to about 400 workers, include planning applications for more than 10 miles of vehicle-testing tracks with high speed sections, hills and off-road routes to put its new electric cars through their paces.

Although only recruiting about 300 more automotive workers at present, planning details show the 45,000-square-metre site will ultimately have space for more than 2,000 people. In addition to the testing track, there will be a cafe, sports centre, recreation space and supporting technical facilities.

Dyson has yet to make a decision on whether it will mass-produce its electric vehicles in Britain once testing is complete. Although it designs and develops products in the UK, supporting high-value jobs, it manufactures them in cheaper locations such as Singapore and elsewhere in the far east.

The company employs more than 12,000 people around the world with about 4,800 in the UK, centred around Malmesbury.

Alongside its vacuum cleaners, hand dryers and car development, the company is working on battery technologies, high-speed electric motors, vision systems, machine learning and artificial intelligence.

Despite difficult trading conditions facing many firms after the Brexit vote amid heightened political uncertainty, Dyson has not changed his view that leaving the EU would be best for the country.

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Before the referendum he was among the most prominent business supporters of Britain leaving the EU despite fiercely vocal support for remain from many other senior figures in business and industry.

“Brexit can supercharge British technology and refocus minds on global trade if only we grab the opportunity with both hands – the government must embrace it and support British businesses,” he told the Guardian.

Several major industrial companies and carmakers, including Airbus, BMW and Jaguar Land Rover, have warned a hard Brexit would trigger a reassessment of jobs and investments in Britain. Economic growth has slowed since the referendum, while households are more than £900 worse off, according to the governor of the Bank of England.