Fuel efficiency has increased, the industry is just not always optimizing for the miles per gallon metric. The Model T 4 cylinder made 20hp. There are 4 cylin

Fuel efficiency has increased, the industry is just not always optimizing for the miles per gallon metric. The Model T 4 cylinder made 20hp. There are 4 cylinder motors today that make 200+hp and go 20+mpg in the vehicles they are used in. The fuel is obviously being used more efficiently. Additionally, modern engines and their exhaust systems control particulate matter in exhaust to a much higher degree than ever before. These systems rob efficiency from the actual energy output of the motor, but have been deemed a metric that should be optimized ( by the general public and regulations).