Fuel Efficiency And Motorsports

The word "efficiency" has become somewhat despised in the eyes of some motorsport fans. From the introduction of regulations to improve fuel efficiency, to drivers being told to save fuel during a race. After all, surely the focus in racing is to be as fast as possible. So why should motorsports focus on the amount of fuel used? 

In truth, there is more to "efficiency" than the simple notion of using less fuel. It's also the matter of getting the most out of the fuel you use, and reducing any wasted potential. 
Fuel efficiency has always been a major factor in racing. Obtaining a balance between power generated, and the amount of fuel burned to produce that power. 

A less efficient car will require more fuel to produce its power, resulting in a car that needs more fuel over the course of a race/event, this can take the shape of heavier fuel loads, or more frequent stops to restock on fuel. 
Needless to say, if you are able to produce the same amount of power as an opposing team, but with the use of less fuel, you are at an advantage. And that is an advantage teams pursue as part of their efforts to win races, making it one of the driving forces in motorsport development. 
Having a more efficient engine allows you to get away with loading your car with less fuel. Less fuel lowers the weight of your car. A lighter car give better performance through acceleration, braking, and helps reduce excessive forces to components such as tyres and springs. Running less fuel also reduces the variation in running weight as fuel is burnt off during a race (from full tank to empty), so you would be able to configure your car for a more consistent running weight. 

A more efficient engine can help you to run the car for an extra lap or two before pitting, reduce the time of pit stops (with less fuel needed to complete a stint), or could result in requiring less pit stops over the course of a race (saving cumulative time lost in the pit lane). All in all, giving more flexibility to strategies.  

There are also external impacts. By consequence of less fuel being required, less fuel has to be transported to races. Which in itself saves energy (and costs) of logistics. 

But that's not to say using less fuel is the bottom line in gaining an advantage. As I stated before: it's the balance between power generated, and the amount of fuel burned to produce that power. So if burning extra fuel is worth the resulting increase in power over your rivals, you're still playing the numbers game with efficiency. 
Furthermore, the pursuit for efficiency isn't limited to combustion engines. Even the likes of Formula E is a battle of efficiency. With teams designing drivetrains to get the most out of the supplied battery power. Transferring more power to the wheels (and from the wheels through regenerative-braking), whilst limiting the amount of energy lost through components; thus aiming to reduce wasted energy. 
Motorsport will always be about resources, and getting more out of them than your opponents. 
Remember, it's not about being as fast as possible, it's just being ahead of the next car.