Q: “I was having a discussion with a buddy about fuel management while racing. I know that if things are getting dicey, drivers will start to coast at the very end of a straight, for example. But how common are other techniques, especially in long endurance races? Is short shifting common? Will people be running 90% throttle down the Mulsanne Straight at Le Mans if they’re not feeling threatened? FWIW, this conversation was born from laughing at the number of times in movies that two cars will he racing down a straight and the drivers will then do something (downshift, upshift, more throttle) to jockey for position instead of simply being wide open to redline in the first place.”
A: Yes, doesn’t that drive you nuts when you’re watching a Hollywood version of racing and they shift a few more gears and push down on the throttle more?!
Managing fuel consumption is pretty much done with early lifts before brake zones, and short shifting. Being a little smoother when applying the throttle will also help, but rarely would a driver be at anything less than 100% on a straight. Alex Rossi won the Indy 500 by conserving fuel in the last few laps, and I think he was at something less than 100% at times, but again, that’s rare – it’s almost coasting.
Holding the throttle at 100% uses less fuel than the action of applying and lifting off the throttle – it’s the change in throttle that uses the most (although that’s not much of an issue now, but was years ago with carburetors).
It’s almost surprising how much fuel can be conserved by lifting out of the throttle a second or two before the brake zones, as well as just being a little smoother when applying it coming out of a corner.
I got a lesson in fuel saving technique this weekend during an endurance race. This could well be obvious to everyone else but in case I’m not the only one…when the strategy guy asked me to save fuel with a lift at specific corners they observed that I would lift, then go to brakes with a longer, lighter pressure. That’s wrong…not because it affects fuel but because it gives up more lap time than you need to waste.
Instead what I was coached to do was lift, coast counting two seconds off then threshold brake hit actually a little closer to the corner than normal…which you can do because the car does slow a bit while coasting so the terminal velocity as you go to brake is lower than the terminal velocity would be when you accelerate all the way to the start of braking point. Doing it mechanically this way there really wasn’t much drop off in lap time and it really did help stretch the fuel on board.
Thinking about it now, I wonder if it wouldn’t be even better to push in the clutch once you lift off the throttle to avoid engine braking…although I suppose that might complicate rev matching for a downshift in the braking zone. Or maybe I’m just overthinking it! 😉