cars are getting better

The current model year is better than earlier years for fuel economy and CO₂ emissions.  The EPA report and executive summary contain a lot of interesting information and the summary is a quick read that makes the main points.

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Introduction

This report summarizes key trends in carbon dioxide (CO₂) emissions, fuel economy, and CO₂- and fuel economy-related technology for gasoline- and diesel-fueled personal vehicles sold in the United States, from model years (MY) 1975 through 2012. Personal vehicles are those vehicles that EPA classifies as cars, light-duty trucks, or medium-duty passenger vehicles. The data in this report cover the MY 1975-2012 timeframe, supersede the data in previous reports in this series, and, for many important reasons, should not be compared with data from previous years’ editions of this report. Most CO₂ emissions and fuel economy values in this report have been adjusted to reflect "real world" consumer performance and therefore are not comparable to CO₂ emissions and fuel economy standards.

CO₂ emissions rates and fuel economy values reflect a very favorable multi-year trend beginning in MY 2005. Data for MY 2011 are final, whereas data for MY 2012 are preliminary and based on projected vehicle production values provided to EPA by manufacturers. The fleetwide average real world MY 2011 personal vehicle CO₂ emissions value is 398 grams per mile (g/mi) and average fuel economy is 22.4 miles per gallon (mpg), both slightly worse relative to MY 2010. Preliminary projections for MY 2012 are 374 g/mi CO₂ emissions and 23.8 miles per gallon, which, if realized, would be all-time records and amongst the largest annual improvements since 1975.

One factor which almost certainly contributes to both the apparent slight worsening in MY 2011 and the large projected improvement in MY 2012 is the reduction in MY 2011 car and car parts production in Japan in the aftermath of the March 2011 earthquake, tsunami, and nuclear disasters. While it is impossible to project the precise impact, EPA estimates that the fleetwide average MY 2011 CO₂ emissions and fuel economy values would likely have been similar to or slightly better than MY 2010 levels if car production from major Japan-based manufacturers had not been constrained by the tragedies. Likewise, the improvement projected for MY 2012 would be somewhat smaller.

For more discussion of the key conclusions of this report, see the Highlights below. 

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But there could be much greater progress - electrification of a larger part of the fleet and weight reduction would seriously improve the results.