pro_engineer — fuel

How much fuel to take — and how to save it without losing time

Fuel you do not burn is weight you carried for nothing.

Every litre in the tank is a tenth you are giving away somewhere, and every litre you are short is a race you do not finish. The arithmetic is small enough to do in your head and almost nobody does it, because the numbers are never in front of you at the moment they matter.

WHAT FUEL COSTS YOU

Ten litres is about seven and a half kilograms. In a GT3 car, ten kilograms is roughly a tenth of a second a lap.

Starting a race with 100 litres instead of 50 is about half a second a lap — for as long as it takes to burn the difference. Over a stint that is a pit stop's worth of time carried around for no reason.

Which is not an argument for running dry. It is an argument for knowing your consumption to within a tenth of a litre instead of adding “a couple of laps spare” and hoping.

THE ARITHMETIC

Three numbers: how much you burn a lap, how many laps are left, and what you are carrying. Everything else is a consequence.

Consumption per lap — measured over a stint, not guessed from one lap. A lap behind traffic and a clean one differ enough to matter.
Laps remaining — on a timed race that is the clock divided by your pace, and your pace is not your best lap. It is your average one.
The margin — a formation lap, a safety car, and the fact that a car that runs out on the last lap scores nothing.

LIFT AND COAST

The efficient way to save fuel, and the reason it works is that you were going to throw that energy away anyway.

Throttle | ____
         |     \
         |      \_______
         | Full | Coast | Brake |

Lift about a hundred metres before the braking zone, coast, then brake normally. The car slows on its own drag for the part of the straight where you were about to slow it with the brakes — so the lap time cost is small and the fuel saved is real: around half a litre a lap.

What it is not is lifting mid-corner, which unsettles the car, or short-shifting, which costs more time than it saves unless the engine map is doing something unusual.

THE NUMBERS WHERE YOU CAN SEE THEM

Pro Engineer answers the question first and shows the working underneath: how many laps are left on the fuel you have, how many on the clock, and how many on the tyres — and which of the three runs out soonest, which is the only one that decides anything. The arithmetic stays on the page, because a number with no working shown is a number nobody trusts twice.

Strategy screen in RG Pro Engineer: laps remaining on fuel, on the session clock and on tyre life, with the arithmetic behind each — Fuel, the clock and tyre life — and which of them bites first.

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