Toyota (NYSE: TM - News) and EDF are teaming up to develop recharging points for plug-in hybrid electric cars in a key step forward for the emerging vehicle technology.

The Japanese carmaker and French utility are due next week to announce an agreement to develop electricity infrastructure to serve the plug-in cars Toyota plans to roll out in a few years' time. Only a few cities, London among them, have recharging points.

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The step is important as the future commercial viability of plug-ins will depend in large part on wide availability of recharging points.

EDF's deal with Toyota is expected to cover France initially but could be extended to other countries. The group also owns utility companies in Germany, Italy and the UK. Having adequate electricity infrastructure for the cars is important in Europe, where more motorists park on city streets overnight than in the US.

Toyota's partnership with EDF on plug-ins is not the first between a carmaker and a utility. In June, Ford Motor (NYSE: F - News) announced a deal with Southern California Edison to install rechargeable batteries in 20 Ford Escape sport utility vehicles, starting this year.

In July, Toyota announced it had developed a plug-in vehicle and become the first manufacturer to have one certified for use on public roads in Japan. Plug-ins promise to deliver a longer driving range and lower running costs than the current hybrid cars, of which Toyota is the market leader.

Separately, GM is due to unveil a new plug-in model in Frankfurt this month under its European Opel/Vauxhall brand in a further sign of its apparent intent to develop and sell the new vehicles globally. GM executives describe plug-ins as the next big paradigm shift for an industry under legislative pressure to lower emissions.

Like other plug-in models GM showed in Detroit and Geneva this year, the Opel Flextreme to be shown in Frankfurt on September 10 will be powered primarily from a large battery that drivers can recharge from a wall socket or any other power outlet. But, unlike the Chevrolet-branded Volt it showed in Detroit in January, whose battery-powered electric motor is backed by a gas-powered engine, the Flextreme's "range extender" will be a 1.3-litre diesel engine.

GM's Opel Flextreme to be shown in Frankfurt is, like the Chevy Volt, a "concept" vehicle common to motor shows. However, GM has devoted 150 engineers to the range of vehicles it is developing under the name "E-flex," and says it plans to sell plug-ins in the US, Europe, and Japan.

The size and future cost of the lithium-ion batteries to power plug-ins are a hurdle. GM has awarded contracts to Germany's Continental and a unit of South Korea's LG Chem to develop batteries.