The firm took delivery of 20 Fiats last year and will receive 30 more over the next few months. All are powered by normally-aspirated 1.9-litre diesel engines and are liveried with the company's insignia.
Paul Swanick, national sales manager, said: 'We have enjoyed a good relationship with Fiat for the past two years and chose the Fiat Scudo as it is far superior to its competitors in terms of space and reliability.
'The back-up and service we receive from Fiat is second to none.'
Vehicles are supplied to National Windscreens through Sanderson Albany Lease and were prepared by Fiat dealer CD Bramall of Plymouth, Devon.