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Originally Posted by lucid
Yeah, right, you are telling me that tests of different cars in different weather conditions (wind, temp, pressure, etc.) and especially with different drivers is an apples to apples comparison!? (Don't tell me they control for the driver effect by hiring pros or something). Get real. See Bruce's post on this forum about the effect of such variables on a simple 0-60 test. Then people pick on tires and start splitting hairs as if they are the only variable here. The only way you will get a somewhat apples to apples comparison is if you test the cars back to back with the same driver although weather conditions can still vary and one car might suit the driver's style better than the other.
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You and I agree to disagree on this. There is nothing you can do to make an exact comparison, as you say, and even if you do the same-day, same-driver thing, there are the potential differences you mentioned, plus there will always be car to car variation, even to the extent that the environment may affect one car slightly differently than another "exact" car.
All that said, my belief is that posted "best" times for the Nurburgring are fundamentally pretty representative of the car's capability, down to perhaps a couple of seconds per lap - or at least in that vicinity.
I believe that to be so for the following reasons:
1) The manufacturers are striving for best times (amongst other things), so it's very reasonable to assume that they will make sure the car or cars they've brought to the site will be in perfect tune, and everything that may affect power, handling and braking will be well attended to.
2) As I understand it, manufacturers typically reserve the 'Ring for days or even weeks in a given year, for basic testing, but also to make sure they run a gamut of conditions. They come armed with enough data in regard to general and 'Ring-specific information so that when they leave, they know they've gotten a representative sample of the car's best performance - or not. If not, they'll be back. It remains to be seen, but when BMW let it out that they were doing 8:10s or so, they may have been a little disappointed (as I was), so definitely more to come. They won't stop until they're satisfied they've got a representative time, whatever that may be.
Quote:
Originally Posted by lucid
Did you read what I wrote. Did I say anywhere in there that modifying the engine would not make the car non-stock? Read again why I set the tires apart from the engine: one is expected to last the lifetime of the car, the other is expected to be a variable during the lifetime of the car, and replaced within the first year for a high performance car like the M3.
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I fundamentally disagree about tires. If the car comes with Michelin Pilot Sport Cups from the factory (either as standard or as an option), then it's perfectly fine to test that way, but if not, then they shouldn't be used to establish a standard for that car. First of all, they make a really big difference (on the order of a second per minute of lap time), and second of all, many (most) manufacturers of high performance cars stipulate an exact tire design that is specific to their car, and the tire manufacturers are happy to go along to get the business. The E36 and E46 M3s had model-specific Michelins on them, and so will the new ones, whatever the tire manufacturer. Swapping to "standard" PS2s on a given model *will* have an effect on lap times and handling characteristics, as will a switch to another brand of "equal" tires.
Allowing anything but either standard or optional rubber means you get hopelessly mired down in trying to equate yet another variable, in this case one that does not lend itself to accurate "adjustment".
Quote:
Originally Posted by lucid
You don't need factory tires to be able to extrapolate from data if that's what you really want to do. All you need is to document whatever tires were used in the test, which is what I said in my initial post, and go from there.
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I can't imagine what "go from there" actually relates to in real terms. Simple tire changes to even "equal" tires of another make can and will have significant effects on lap times - and unless those particular tires have been exhaustively tested on that car, there's no possible way to calculate anything back to a standard.
I understand where you're coming from, since your belief is that there is a broad latitude of plus or minus in the published times, but of course that is where we fundamentally disagree. I think the published times are likely to be representative to within a couple of seconds per lap, and you think it's way more. So be it.
Bruce