Indy 500; why do they do this?

Not just Indy, but on big, fast ovals, the line exits the turn high, then swings way down along the long stretch before going high again to enter the next turn. Why not just stay high and save a few yards? Maybe something about how the air behaves along the wall?

momentum for the upcoming turn

Banked turns run downhill if entered high & apexed low.
Also serves to break up the draft.
On a bullring that's not as prominent as tracks with long straights.

I'm more annoyed that they didn't red flag the race after that last wreck, and let 'em have a 3-lap shootout for the win.
Then again, that could have led to some real carnage, so perhaps being conservative with that was wise.
Kind of a shame that Dixon owned the place all day, but had to ride out the ending yellow laps in 2nd.

Its primarily aero, first car does, all the rest slower cars need to stay in draft and follow. Aero reason, there is more drag when the car at high speed has to to push air against a nearby stationary object, then against free air, so, move away from the wall, if the corner line doesn't say otherwise. I'm sure there is some compromise involved, but the fact they do it says what they feel.

Its easy to visualize the amount of air we are discussing when watching the fence banners on th indy street road race circuits when the cars pass nearby at speed..

Several reasons mentioned already.

Also they are trying to keep the car behind them from getting the inside. Forcing them to try to pass on the outside.

I haven’t really watched it in for years and tuned in for the last 30 laps or so. Then they went and ended it like that. Total bull crap.

Yeah wish they would have red-flagged it. But ultimately I don't think it would have changed the end result.

Dixon had the strongest car all day up to that point--seemed like he could pass at will. But the last 20 to 30 laps he didn't seem like he could close the gap to Sato. Not sure if the sun going down changed his setup or what, but Sato was steadily walking away from him and had gotten lapped cars between them when the crash happened.

A solid clue is they also do it every lap, on a qualifying lap, when they are the only car on the track.

I'm pretty sure they do it because that is what the car wants to do. They can fight it but he car wants to head down hill coming out of the last corner. Then as they get on the flat they can start to set the car up for the next corner. I think it is the fastest way around the track even if it doesn't look like it. If you tried to hold the car up against the wall coming out of the last corner you would have a fight on your hands. The car wants to head down to the inside and it won't want to go back up until it gets settled.

Maybe if they run stagger, otherwise its only the incline of the straightway to deal with?

I don't see "fighting" as much of an issue, with a car generating in excess of its weight in DF at speed, and that they are not picking a straight line down the entire straight for the bottom of the incline, but more of an exit corner, and drive to center of track, at end, drive to outside by the wall to increase the driven corner radius as much as possible for next corner.

Tire stagger AND cleaner air. With tire stagger the car will always be faster turning so they carry the turn as far as they can then start the next turn. They would also have cleaner air down low - nothing buffeting off the wall. From a safety standpoint I'd like to stay as far away from the wall as possible, if anything goes wrong you have a lot more room to maneuver.

So regardless of all this, why do the NASCAR boys run up against the wall ?!?!?

I thought in modern times, they don't, like at Pocono for example?

Petty started running up against the wall in the turns after he clobbered the wall at Daytona I believe in 1967, and hurt his neck, to lesson the impaxt angle I believe, and he also post wreck fabricated the "petty strap" ( a crude precurser to a HANS?)

Yeah I figured this too, its like in bike criteriums when strong teams will go to the front of the pack and direct the race like this so other racers can't cut up the inside to get to the turn ahead. It's very effective, but not always easy to pull off.

Because the the "inside" , away from the wall is faster?

Yep, in a 90-degree corner crit it's a shorter distance to the inside of the turn and dive bomb in ahead of the leader if he leaves the inside open.

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On a 50ft wide track, its shorter by maybe 3' ? on a long straight, not enough for a pass
It also means following car loses the draft
It sets up the following car for being made a classic "crossover" pass in next straightaway, because they either have to reduce their corner speed slower then the passed car because they made made the corner radius smaller on entry or widen their exit corner radius if trying maintaining speed and risk driving into the marbles.
Most of the above assumes cars/drivers of equal performance, unequal, they usually just pass at any chosen opportunity.