International research consultancy firm McKinsey has just released the latest of its reports on electric cars, placing the U.S. ahead of other countries when it comes to electric car adoption.

Taking into account nine variables likely to influence investment in the electric car sector such as cost of production, electricity rates, consumer interest and government incentives for electric car purchase, McKinsey has produced an index of countries most likely to lead the emergence of electric cars as a means of mass transportation.

Thanks to the continued support from the U.S. Congress and Obama administration, McKinsey views the U.S. as the most likely to lead the switch to electric cars from gasoline powered ones.

Of the twelve countries ranked in the report, China and Germany tie in third place on the index.

Germany has historical precedence for being a world-leader in electric vehicle technology, with many smaller city and neighborhood electric vehicles being made there.

But with many major automakers targeting the U.S. as prime markets for mainstream, highway capable cars like the 2011 Nissan Leaf, 2011 Chevrolet Volt and 2011 Mitsubishi i-MiEV, McKinsey believes the U.S. will lead the global EV market for several years to come.

However, low cost electricity in China and South Korea combined with a host of electric vehicles predicted to be produced in China over the coming decade leads McKinsey to hint that China may lead the electric car market within 20 years.

For now though, the message is clear.

Nowhere else in the world is supporting electric car roll-out with the governmental tax credits, purchase incentives, and charging infrastructure available in  the U.S.--and the variety of models that will become available reflects that.

[Financial Times, requires free subscription]