I'm not questioning the accuracy. I'm saying that if you want to compare times with what Porsche states, you need to measure it the same way i.e include the rollout.

As for 0-62 I suppose it's because I'm in Europe.

But again, if you want to compare times to manufactures claims, you need to include the rollout. What ever NHRA or magazines specify as their standard, has little to do with how manufactures measures the times. It's just as off as rolling a Corvette on an inertia style dyno using STD correction and then compare it to manufactures claims.

 

There was an Engineering Explained about the 1-ft roll out...really like timing 5-60mph as opposed to 0-62.5 mph (0-100 kmh). Big difference.

 

Yes, I agree…and pretty sure most people know that. At least i do.

The 1 ft rollout time deduction, I suspect, has it’s origin in American drag strip/NHRA rules…and is an attempt by car magazines, and GPS based car time measurement companies to conform, for comparison purposes, to what the NHRA does. But yes, i would not expect Porsche to use the 1 ft rollout…although they do not specifically state, either way….but left to the reader to make their own assumption.

 

I think anybody that’s taken their car to a drag strip knows about the 1 ft rollout. But I suspect the average driver wasn’t aware of this practice, but became aware when Tesla (musk) bragged the Plaid had broken the 2.0 sec, 0-60, “barrier”….without saying they used the 1 ft rollout, to make that claim. I think Motor Trend uncovered the truth.

Like everything, the truth is in the details. But the fact remains, most automotive reviews, today, automatically deduct the 1 ft roll out. If they don’t, they usually explicitly state as such.

By the way, the 1ft rollout difference is just under 0.2 sec

 

The 1-foot roll is mainly a US practice. It stems from the NHRA drag racing regulation, where there is one foot between the staging timing light trigger beams. It has therefore been a practice for US publications to deduce the 1-foot roll out so that their published 1/4 miles times are representative to those that could be achieved at the drag strip. For consistency, the practice was carried over to time-to-speed metrics too. European publications do not discount the one-foot roll out and, as you stated, usually publish 0-100km/h (0-62mph), which both combined can lead to a 0.3~0.5 second difference between US and EU numbers. EU manufacturers also tend not to omit the one-foot roll out from their US published specs.

And we’re 100% on the same page regarding power ratings. Not many folks understand there is a massive difference between testing an engine in steady state on a bench brake dyno vs testing a whole drivetrain in transient state on an inertia dyno.

 

Just to be clear, Porsche (on their US web sites) uses 0-60mph, not 0-62mph. I will assume that if they meant 0-62 mph, they would have stated? Regardless, I think the Porsche time does NOT subtract out the 1 ft rollout time, like Tesla does. Subtracting out the 1ft rollout time would reduce the 0-60 time by about 0.2 sec, bringing it from 4.0 sec (non chrono) on the Porsche site, down to about 3.8 sec. Further, and as we all know, Porsche does over/underestimates their specifications, such as time and HP figures, respectively..

 

True for US publications. However, pretty much everywhere else in the world, the one-foot roll out is not removed. The things is, while it might be appropriate for 1/4 mile, IMHO, it is a bit of an overstretch to extend this one-foot foot roll out notion to time-to-speed metrics. It mattered less in the days when cars needed 10sec to get to 60mph, but on 2.0~3.0sec cars, the relative difference is much more significant.

 

Yes, we are on the same page. Porsche USA use 0-60mph including the one-foot roll out.

My point was when comparing numbers published in US vs EU magazines.

As for power claims, this is quite regulated. The perception of under rating stems from how modern turbocharged engine behave and the testing standard specified in the regulation.

 

Totally agree. I’m not arguing for the need to do this, just that it’s relevant if one wants to start comparing numbers. From 2019, C&D started subtracting out the rollout…so, if one is comparing to C&D numbers, for example, you need to take that into account. The default for Dragy is to subtract out the 1 ft rollout time…but you can also set up a custom setting that does not include.

 

My understanding is that C&D numbers have always had a notion for the one-foot roll out, this is not new. What is new is that their latest timing gear is able to actually measure it instead of just estimating it.

 

I think the take-away, when comparing times, or HP numbers….one really needs to understand the details of how, and under what conditions the measurements were made.

 

Well, I’m sure they had a “notion” of it, but my point was - From 2019,on, C&D substrates out this 1 ft rollout number from their run times (from more accurate measurements). Before 2019, they “estimated” by starting the clock at 3mph (not 0). C&D states that the different methods lead to about 0.1 sec difference, with the more accurate 1 ft rollout technique resulting in about a 0.1 sec quicker run time, compared to the previous estimate used by C&D, pre-2019.

https://www.caranddriver.com/feature...hange-rollout/

 

It’s not that black or white. They used to start the clock at 3mph to estimate the 1-foot rollout because that was representative of what speed most cars reach after a 1-foot roll out.

I just wanted to clarify here that C&D numbers “prior to 2019” where not “pure” launches from a dig either (as is done in EU publications).

EDIT: You edited your post while I was replying. We’re saying the same thing…

 

Yes, of course. As I said, the results are in the details of how the measurements are made. Since I live in the US, I mainly read US sources such as C&D and MT. Those are the numbers i compare my own measurements against, not European numbers/tests.

 

^ This