For both markets, rapid technology diffusion is found in recent years, largely as a response of vehicle manufacturers to increasingly stringent regulatory standards. Yet there are differences in the mix of technologies in both regions. In the U.S., manufacturers tend to focus more on VVT, GDI, hybrids, and continuously variable transmissions (CVTs) or transmissions with six or more gears, whereas in the EU there is stronger growth of diesel engines, stop/start, and turbocharging. Vehicle characteristics in both regions differ as well. Passenger cars in the U.S. are generally heavier, bigger, and more powerful than in Europe, which results in higher average fuel consumption and carbon dioxide (CO2) emission levels in the U.S. However, in both regions vehicles have tended to become more powerful and heavier while deploying increasingly high levels of technology and reducing official type-approval CO2 emissions and fuel consumption. As a result, both regions met their respective 2015 CO2 standards ahead of time. Some technologies seem to be driven not only by CO2/fuel efficiency regulations, but also by other influencing factors, such as complementary regulations and incentives, differences in the enforcement of vehicle test procedures, and marketing efforts, as can be seen, for example, in the markedly different deployment of diesel and hybrid electric cars in the U.S. and the selected EU member states.
In retrospect, the amount of technology deployment required to meet the EU’s 2015 vehicle CO2 target and in particular the associated cost increment is found to be significantly lower than expected at the time when the respective regulation was developed. Additional manufacturing costs to comply with future CO2 standards are as of yet uncertain, but it is concluded that rigorous bottom-up methods should be the preferred approach for estimating future technology potential and costs.