Vauxhall has added an engine stop-start system to the 2.0-litre diesel engine in its Astra model.
Average economy for the hatchback has been improved to 62.8mpg (from 57.6mpg) and CO2 has dropped to 119g/km (from 129g/km). This means these models drop a company car tax band to 13%, and private buyers will pay just 30 a year in road tax.
Vauxhall has also installed its Cleantech Combustion Technology, which reduces engine noise and includes cleaner engine combustion so it runs more efficiently. The company also says that this and the stop-start technology will be in most of its models by spring 2012.
The 2.0 CDTi Astra stop-start models are on sale now, with prices starting from 22,410 for the hatchback and 23,430 for the estate.