A government-commissioned report warns that Germany\'s plans to put 1 million electric cars on the road this decade may do less to curb emissions than tightening efficiency standards for gas guzzlers. Tightening fuel efficiency standards could do more over the next twenty years to cut Germany\'s greenhouse gas emissions than government plans to roll out electric cars. By 2030, electric cars may only cut automotive emissions by 6 percent, according to a study for the government carried out by the Institute for Applied Ecology, a green think tank known in Germany as the Öko-Institut. In contrast, the study said smaller engines and lighter building materials for conventional vehicles could do far more to cut emissions over this period, provided EU rules up to 2015 are extended. \"If petrol-powered cars are made significantly more efficient by 2030, they alone could reduce the greenhouse gas emissions of passenger car transport in Germany by 25 percent,\" said Florian Hacker, one of the institute\'s researchers. While welcoming investment in electric mobility, the study warned that Germany\'s grid would need to supply a lot more renewable energy before electric vehicles could start contributing significant cuts to automotive emissions. Electric potential An electric carGermany needs a network of battery exchange stations The study found government ambitions to get 1 million electric cars on the road by 2022 was realistic. However, it also said electric cars would still only constitute a minor fraction of the car fleet by 2030. As the technology stands, it will only be able to cover \"two-thirds of journeys\" and will be best suited to inner-city trips. Fully electric cars presently have a maximum range of 160 kilometers - after which batteries have to be recharged (a process that takes five hours), or exchanged. For longer journeys, the industry is offering plug-in hybrids, which combine electric and conventional technology. The institute says these cars have the greatest market potential. \"Electric vehicles could have a market share of about 14 per cent by 2030,\" said Hacker, \"[it could] even reach about 30 percent. But according to our calculations most of these cars will be plug-in hybrids.\" Parallel development But the Öko-Institut says electric cars will only make a significant contribution to reducing carbon emissions if all their energy comes from renewable sources. Only then will electric cars by emission-free. It\'s an important selling-point and one that may prove only partially true for some time to come. \"Berlin has plans to expand the generation of renewable energy, but those plans do not take electric cars into consideration,\" said Hacker. \"As things stand, electric cars will present an additional demand for energy and it will have to come from things like coal.\" To meet the challenge, the Öko-Institut is calling for renewable energies, such as wind, biomass and solar to be expanded more rapidly than current plans foresee, and in parallel with the development of electric cars. \"Otherwise there is a danger that we will fail to meet the energy demands of 2022 or 2030,\" Hacker said. Car industry supports electric Germany\'s automotive industry association (VDA) supports the development of electric cars - especially for use in urban environments. Like the Oeko-Institute, the VDA sees electric cars as part of the solution to tackling the climate impact of the automobile sector. He said efficiency gains could cut conventional cars\' emissions by 25 percent, but probably no more than that. \"We could use smaller engines and we could make the vehicles lighter,\" said spokesman Eckehart Rotter, \"but only up to a point because we don\'t want to sacrifice safety standards.\"