The way cars are designed and engineered is changing rapidly to meet the challenges of emissions regulations and consumer expectations for fuel efficiency.
There has been a great deal of media coverage on how the regulated fuel economy ratings for cars are becoming irrelevant predictors of results in the real world. As regulations on CO2 or fuel economy get tougher, the gap between the reported numbers and actual consumer experience increases. Regulators and consumers alike think they are achieving better results than they are. Recent studies indicate that the gap between sticker and actual performance is 30% on average.