Volkswagen's Touran and Sharan MPVs can now be specified in the company's 'eco' trim, Bluemotion.
The cars have had a range of modifications such as aerodynamic tweaks, longer gear ratios and low-rolling-resistance tyres fitted to improve fuel economy and reduce carbon dioxide emissions.
As a result of the modifications, both models drop down a VED road tax band.
The Touran Bluemotion, fitted with a revised 103bhp 1.9-litre diesel engine, is capable of 52.3mpg and emits 144g/km of CO2. That compares with 47.9mpg and 156g/km with the standard 1.9 TDI model.
Prices for the Touran Bluemotion start at 16,725, about 300 more than non-Bluemotion models.
The Sharan, powered by a 138bhp 2.0-litre diesel engine, emits 159g/km of CO2 and is capable of 47.1mpg, compared with and 175g/km and 42.8mpg of the standard model.
The Sharan Bluemotion costs from 21,290, a 600 increase on the non-Bluemotion model.
Both cars are also fitted with particulate filters, which reduce emissions of nitrogen oxides and carbon particulates.