Aerodynamics are one of the fundamental determinates of a racer's performance. Which is why the team behind the Nissan Deltawing - a 300bhp, 500kg mentalist set to compete in this year's Le Mans - have been scrutinising its slipperiness so carefully.
The boffins have had to be super-vigilant with the DW, too - the engine's half the power of a full-fat Le Mans Prototype and, while it carries just half the heft of an ordinary LMP1 car, it can only produce half the drag to remain in contention.
If the Deltawingers get it right the car will only nibble through half the fuel and half as many tyres. Which is useful when you're racing for 24 hours...
When we spoke to Marin Brundle, who'll be racing against it at this year's race, he said: "My concern is that it'll be too fast. It's got low drag, I think it'll be a real nuisance for us, because it'll be faster in different places. The people who put that together are smart people - I heard it's pulling over three lateral g already.
"It's not allowed to win anything [the DeltaWing is racing in its own category] but I bet you it'll be surprisingly quick. I think it's a very bold adventure, and I'm looking forward to seeing it out on track." You can read more of his thoughts here
Also, look out for a very special feature in next month's Top Gear magazine (out on April 25) - we've managed to get up close and personal with it...
Now watch. Then look at these lovely pictures of it
What do you make of the Deltawing, TopGear.commers?