Looking back over the last several decades, consumers have greeted and cherished a variety of iconic vehicles. In the second half of the 20th century, roads became littered with Ford Thunderbirds, Chevrolet Impalas, and the Oldsmobile Cutlass. Each model offered what the general population wanted: a powerful engine and, for that time, a comfortable ride. They also shared another common feature: harmful emissions and poor gas mileage. Back then, we didn't know the effect of emissions, and gas-guzzling vehicles weren't an issue with the next-to nothing price of fuel. However, times have changed; they always do.