Opel is promoting the green credentials of its new Zafira that runs on compressed natural gas and which it is now on sale in Germany.

A total of 500 Zafira CNGs have already been registered in Germany and the clean car goes on sale in the 'principal market' of Italy this month.

The vehicle's engine, based on the 1.6-litre ECOTEC petrol unit, is described as 'monovalent' which means it is optimised to run on natural gas although petrol can still be used.

Opel said the seven-seat vehicle 'is entirely suitable for day-to-day use and provides the same driving pleasure as the comparable petrol-engined model'. It said it offers 'reduced exhaust emissions and also significant advantages in its running costs'.

The manufacturer added: 'Among the significant advantages of natural gas fuel are high environmental acceptability and economy. The pollutant emissions compared with petrol and diesel engines are in some cases 90% lower, the CO2 emissions are only 145 grams per kilometre,' the manufacturer said.

'Similar benefits become clear in connection with fuel costs,' it adds, using German fuel prices as an example. 'At a consumption of 5.5 kilograms of natural gas per 100 kilometre, the Zafira 1.6 CNG can be run at about 30% lower cost than the Zafira with 2.0 DI ECOTEC turbocharged diesel, and as much as 50% more cheaply than the Zafira with 1.6 ECOTEC petrol engine.'

The manufacturer said natural gas enjoys a tax concession in many European countries until 2009 when it is used as a fuel.

'For this reason, and also because vehicle tax and insurance premiums are distinctly lower in some countries, the additional cost of €1,420 charged for instance in Germany for the Zafira 1.6 CNG compared with the Zafira 2.0 DTi is recovered in as a little as 1.6 years if the vehicle is driven for 20,000 kilometres annually,' it added.