Available in both saloon and estate versions, the Insignia has proved to be more popular than the BMW 3-Series and Ford Mondeo, according to the latest figures from the Society of Motoring Manufacturers and Traders.
Vauxhall sold 7,826 Insignias in March 2011, an increase of nearly three quarters over the previous year as buyers downsized from expensive premium saloons and estates.
The Vauxhall Insignia was the sixth best-selling car overall in the UK in March thanks to its success in the business and fleet sector.
Fleet sales increased by 147 per cent in March as UK businesses looked for less expensive cars to run in their fleets.
The Insignia, which was awarded the highly prestigious European Car of the Year title when it was launched in 2009, features an updated interior with upmarket upholstery and high levels of equipment to target the business market.
One model sure to appeal to business customers is the Vauxhall Insignia ecoFLEX. Available as a saloon or estate, the ecoFLEX model comes with an efficient 2.0-litre CDTI engine developing 160bhp.
Fuel consumption is an impressive 57.9mpg and CO2 emissions are as low as 129g/km on saloon versions. This is particularly important because road tax and company car tax are both based on the level of CO2 a car emits.
The success of the Insignia led to Vauxhall being the only manufacturer to boast three cars in the top ten best-sellers in the UK in March.
The Vauxhall Corsa supermini was the third most popular car, while the British-built Vauxhall Astra finished slightly behind in fourth place.
Vauxhall also improved its share of the van market to nearly 20 per cent and the Vauxhall Zafira MPV was the best-selling large people carrier in the UK despite a new model being prepared for later in the year.
"We’re naturally very pleased with these results," said Duncan Aldred, Vauxhall’s Managing Director. "Not only are vehicles like the Insignia, Zafira, Vivaro and Movano leading the way in each of their sectors, but we’re also steadily increasing our market share, year on year."