McKinsey has a 36 page analysis of a path to low carbon cars and trucks in 2020 and 2030. This projection is dependent upon a forecast and assumption for a range of energy costs and on the general availability cost and effectiveness of automotive technology. In the first picture we see the chart of technology and costs for lighter and more efficient regular cars and trucks and hybrids and electric cars.
Big game changers would be algae, seaweed, and microbial biofuels that would be able to displace all or most oil usage and very cheap and good performance electric or plug in hybrid cars.
Some of the recommended measures from the McKinsey Global Institute are removing subsidies for oil (mainly in the middle east) and allow trucks to be longer. A big medium term win would be to not use liquid fuel in power plant biolers.