Today, there’s an estimated 1 billion cars on this planet. As Daniel Sperling explains in his book Two Billion Cars: Driving Toward Sustainability, there’ll be roughly twice as many in 15 years, with that number expected to triple by 2050. You think there’s smog in Los Angeles now!?!

So, we welcome news of a joint international agency effort to produce a ‘roadmap towards greater global fuel economy’ that would halve greenhouse gas emissions from cars by 2050. The ‘50 by 50′ Global Fuel Economy Initiative (GFEI) attempts to show how annual savings of six billion barrels of oil and 2 gigatonnes of CO2 is achievable through an ambitious world wide program.

The campaign is the result of a partnership between the UN Environment Programme (UNEP), International Energy Agency (IEA) International Transport Forum (ITF) and FIA Foundation- a British nonprofit which promotes environmental protection, road safety and sustainable mobility.

Jack Short, Secretary General ITF said: “We already have the technology and the means to get us on the road to making our cars 50% more fuel efficient – all that is needed are coordinated efforts and actions from both industry and governments.”

David Ward, Director General FIA Foundation said: “This initiative can have a huge impact on the motoring public. Through tax incentives and information campaigns it would help encourage consumer demand for more fuel efficient cars. This is not an agenda for some point far off in the future. Our 50% fuel efficiency target requires us to change direction and take important actions right now.”

Some good quotes, but not a ton of specifics. We’ll keep an eye on whether ‘50 by 50′ can convince governments and car-makers, as well as drivers, to rally behind these measures (whatever they are, exactly).