F1 Fuel Saving in 2014

F1 this year is going to be very different from any previous season. The technical regulations open the doors to turbos connected to electric motors, 120kW KERS motors, 4MJ batteries, and wastegates. The ways in which the 2014 power unit can be used are myriad and it will be very difficult for the TV commentary teams to understand the implications themselves, let alone explain them to viewers! However, there are some things we can work from very basic information available online.

Aside from all of the turbo, MGU-H, battery stuff that makes it more complicated for us to understand, there are two parts of the 2014 rules which are very straightforward, from the technical regulations:

5.1.4 Fuel mass flow must not exceed 100kg/h.

And from the sporting regulations:

29.5 No car is permitted to consume more than 100kg of fuel, from the time at which the signal to start the race is given to the time each car crosses the Line after the end-of-race...

First off, let's observe that if fuel flow is limited to 100kg/h, then we know the fuel flow of every car at full throttle (100kg/h!). Let's take an extreme example and look at Monza, the high speed circuit of F1. The race in 2012 was won by Lewis Hamilton in a total time of  1:19:41.22. Monza is 53laps, so that's an average laptime of 90.21s. Depending on which website you get your F1 stats from, a lap of Monza is about 75% full throttle. The remaining 25% is divided into braking (at zero throttle) and accelerating from zero to full throttle. If we say that the split between braking and part throttle acceleration is even, and that the average throttle in the part throttle regions is 50%, then we can approximately represent all the time that's not full throttle by saying that a quarter of that time is full throttle, and three quarters of it is zero throttle. Adding this throttle usage to the 75% full throttle portion we get to 81.3% of the lap at full throttle as an approximation including the part throttle regions. Now, we should translate the FIA's fuel rate into a proper unit:

100kg/h / 3600s/h = 0.0278kg/s

If we multiply our three numbers so far together, we should get fuel use per lap:

90.21s/lap x 81.3% x 0.0278kg/s = 2.039kg/lap

Which is 2.039kg/lap x 53laps/race = 108.06kg/race. Which was fine in 2012, but it's over budget for 2014 by a little over 8kg! So, clearly you can't just smash round the track at full throttle like you did in the good old bad old use-as-much-fuel-as-you-like days. The question is, what's the best way of saving fuel without losing time? As any well informed motorsport fan knows, the most laptime-efficient way to say fuel is to completely lift off the throttle at the end of each straight and coast for a bit before hitting the brakes for the next corner, called 'lift-off', or 'lift and coast'. The reason is that saving fuel at the start of a straight means that you accelerate less and therefore go slower for the whole straight, whereas lifting at the end of the straight doesn't make you slower further down the track because you were about to brake anyway. How much lift-off are we talking about here? Well, if we lift-off at the ends of the straights then we're swapping time spent at full  fuel-flow for time spent at zero fuel-flow, so we save 0.0278kg/s during lift-off. To save our 8.06kg per race we need:

8.06kg / 0.0278kg/s = 289.9s/race

289.9s/race / 53laps/race = 5.47s/lap of lift-off!

No, your eyes do not deceive you (I encourage you to check my maths): this season, at Monza, drivers could have to lift-off the throttle at the ends of straights for an average of nearly 5 1/2 seconds per lap! If we distribute this time mainly over the four longer 'straights' (the Curva Grande is effectively a straight) and a little on the two shorter sections leading into each Lesmo then we might get something like this for an average lift-off schedule:

1.24s on the main straight into the first chicane
1.02s after Curva Grande into the second chicane
0.54s before the first Lesmo
0.54s before the second Lesmo
1.02s into Ascari
1.02s into Parabolica

As you can see, it's not exactly going to be the traditional 'last of the late brakers' scenario into the first chicane, or into any of the corners for that matter. Even if we're overestimating the amount of lift-off by a factor of two, we're still talking about half a second at the end of each long straight.

Of course drivers and teams might decide that lifting-off at the end of the main straight is too costly in strategic terms because it's a prime spot to overtake, or be overtaken. In which case they may not lift there, but they will then have to lift even more elsewhere to save the extra fuel.

There will be races where fuel saving is not an issue, Monaco for example is so slow that it's likely that no fuel saving will be necessary. Monza is an extreme example of a high-speed track where the fuel limit will have a big effect. The other factor that would eliminate the need for fuel saving is the safety car. F1 cars use (relatively) so little fuel when behind the safety car that as few as 4 laps behind a safety car could save enough fuel to complete the race without lifting-off any more.

I can't wait to see how this season plays out, and what strategic effects these radical fuel saving regulations will have.