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Around here the road shoulders have a number of unattended radar devices which display speed. Granted they aren't in places where someone could go fast, but whenever I go through one the display is pretty much spot on what my gauges say. I doubt those devices would display a number lower by 5% because if they did it would encourage whoever reads them (if anyone ever paid attention) to think they could go faster. The usual law enforcement mentality would be to have them display high.
So following your logic, if those radar signs in your area display higher than actual speeds, that's why they match your Porsche speedometer.

In my area there are a lot of 25 and 30 mph speed limit zones with those signs in an attempt to slow residential neighborhood traffic down. But I think they read accurately and although that's much harder to gauge in only full 1 mph increments, my Cayman says I'm going 27 when the sign reads 25, and 32-33 when the sign reads 30.

I have heard the rationale that speedometers read high to discourage people from speeding, but that's BS, once someone realizes their speedometer in inaccurate. I loved the fact that my old Honda S2000 digital speedometer was dead on accurate. Never any question of doing math on 55 - 70 mph speed limits in our area. Even though I like math :D
 

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2007 987.1 Cayman S 6M. 2022 718 Cayman PDK
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So following your logic, if those radar signs in your area display higher than actual speeds, that's why they match your Porsche speedometer.

In my area there are a lot of 25 and 30 mph speed limit zones with those signs in an attempt to slow residential neighborhood traffic down. But I think they read accurately and although that's much harder to gauge in only full 1 mph increments, my Cayman says I'm going 27 when the sign reads 25, and 32-33 when the sign reads 30.

I have heard the rationale that speedometers read high to discourage people from speeding, but that's BS, once someone realizes their speedometer in inaccurate. I loved the fact that my old Honda S2000 digital speedometer was dead on accurate. Never any question of doing math on 55 - 70 mph speed limits in our area. Even though I like math :D
my Cayman says I'm going 27 when the sign reads 25 -> Same thing with my 987 and 718.
 

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A reading from those radar units can be misleading and read low. It all depends on the angle between your velocity and a vector between the radar and your car. When you first approach the sign that angle is near zero if it reasonably low to the ground and far enough away. But depending on where it is positioned on the shoulder, as you get closer that angle grows. At 20 degrees off axis it would measure your speed 6% low. You can observe this by how the reading will often drop by a few mph between first detection and when you pass it. So you have to judge what it says carefully. If it reads a car in front of you until you get close enough, then you really can't trust it much at all.

That kind of error is probably not something the signs or the installers correct for. There is no fixed correction which applies to all approach distances. Since it is not evidence usable in court (at least around here AFAIK), there is no reason to make them more accurate. They are just guidelines and warnings to drivers who may have forgotten how fast they were going.
 

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Oh crap! I didn't know that is what those are for. I thought they were just there to challenge you to see how fast you could go before you got to the sign ;)
We have those in my neighborhood. 25 mph zone. From 26 to 29, the speed numbers flash. Hit 30 or higher, the disco light comes on (strobe light).
 

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122 on Interstate 81 in Tenn last June passing some trucks. Wasn't paying attention to the speed; was watching the trucks turn signals and front wheels for any erratic lane changes (they were all doing about 74 when I went for the pass). Just happened to look down at the digial speed when I cleared the last truck (can't see the analog needle from my seat position) and (in this order) : felt my sphincter tighten, gulp, whoops, foot off the right pedal, looked around for flashing lights, looked up for low flying aircraft (we are talking about Bumblebee where the top is nary up), moved over the right lane, breathe. All of which took about two seconds......
In retrospect my impression was that speed is a non entity in these P-cars. They could run in the 150's all day long and not bat an eyelash. Truly amazing machines.
 

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2018 Cayman GTS
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Discussion Starter · #31 ·
Not a Cayman but i have done 298 km/h (185mph) in my BGTS.
With the tune i should be able to go over 300km/h but the settings have not been good enough to try.
Nothing beats the feeling right? The rush of knowing you may be living your last moments. Wether dead or in jail. 🤷🏽‍♀️😂
 

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Discussion Starter · #33 · (Edited)
For me it's not a top speed run, but to travel :D
I never went faster than 265 on highway and it was around 20 years ago. I don't feel it safe as there is almost no place without other traffic.
I do it frequently and long above 200, but not more than 240 . But I do it with open top too.
Cars and bikes both.
I just drive fast I’m Puerto Rican I’ve been told building fast cars is in our blood. 😁 but about 150 starts feeling fast in our cars. In my out and about middle of no where drives I never go much faster then that but always cruising at 100mph + . I only go above that to see how fast she will go sometimes after a mod or temperature change. I let off right as a I start feeling like “ok that’s enough.” 😬😆 the K 40 really helps me stay out of trouble that and Wayz.. but mostly instinct I guess. 🚓
 

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Discussion Starter · #34 · (Edited)
I have absolutely NOT driven at 145mph; no way - to do so on public roads would be dangerous and irresponsible. I may have done 71 in a 70 zone (once) but I drove to the nearest church and said 25 hail marys immediately. The Rabbi was as confused as I was.
Ya where I live there are roads that are miles and miles long flat roads literally in the middle of no where.. like if something happened they wouldn’t find you for days. Definitely not something you could do safely in town.
 

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Discussion Starter · #35 ·
You've gone way faster than me, but just curious as to whether you've checked the (notorious) amount of Porsche speedometer error at those high speeds?

I used to have a Delorme GPS that plugged into a laptop and gave accurate speed readings to within 0.1 mph. From my former 2005 911S (997.1) here are the results I had printed out to try to get my dealer to address it with Porsche and, if possible, correct the error. The speedometer readings are from the digital indicator not the analog (needle).

Using cruise control and multiple runs:
Speedometer: 40 mph - Actual: 37.8 mph = -2.2 mph (5.5%)
Speedometer: 60 mph - Actual: 56.7 mph = -3.3 mph (5.5%)
Speedometer: 75 mph - Actual: 70.9 mph = -4.1 mph (5.5%)
Speedometer: 90 mph - Actual: 84.8 mph = -5.2 mph (5.8%)

One time on empty highway with passenger noting actual speed on laptop as I hit 110 on the digital speedometer. Multiple times, all within 0.2 mph of 103.6.
Speedometer: 110 mph - Actual 103.6 mph = -6.4 mph (6.2%).

I repeated this with my 2014 Cayman S, but don't have the printout. It was almost identical to the 911S error where the speedometer reads 5-6% too high. Porsche's response was typical BS. First they said it was likely my misreading or Delorme wasn't accurate. Or perhaps my tires were worn down or different size (brand new Michelins with same diameter and revolutions per mile as the OEM Pirellis). In the end they just said "it is within acceptable error", which they claimed could be up to 7% (!!) On my former Honda S2000, its digital speedometer was absolutely 100% accurate according to the Delorme GPS. As soon as the GPS went from 79.9 to 80.0 mph, the Honda digital speedometer switched from 79 to 80. Exactly at the same time, accurate across multiple speeds.

So......at least according to my experience, if you are looking to "actually" break 200 mph, you will need to hit somewhere between at least 211 and 212+ mph on your high-reading Porsche speedometer.

P.S. Can't use the Delorme anymore, it's not compatible with Apple laptops. But my 2022 Cayman GTS 4.0 still has an even greater error in the MPG trip computer - it will consistently indicate that I'm getting 1.5 to 2.0 mpg more per tankful than I actually get when you divide the trip miles by the gallons to fill up. Our BMW's and my daughters' Hondas are spot on, when you check the math against their trip computers. Amazing (and frustrating) that Porsche engineers can produce the best sports cars and can't (or won't) produce an accurate speedometer or trip computer.
That’s crazy we have Waze gps and in both my Porsches and the gps is within a mile at 145. I know tire size changes these numbers significantly like that.
 

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Discussion Starter · #36 ·
Around here the road shoulders have a number of unattended radar devices which display speed. Granted they aren't in places where someone could go fast, but whenever I go through one the display is pretty much spot on what my gauges say. I doubt those devices would display a number lower by 5% because if they did it would encourage whoever reads them (if anyone ever paid attention) to think they could go faster. The usual law enforcement mentality would be to have them display high.
Ya I was gonna say that too mine is always dead on at the lower speeds. But mines of about a mile at 145. Could be the gps that is off a mile though right?
 

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Discussion Starter · #37 · (Edited)
122 on Interstate 81 in Tenn last June passing some trucks. Wasn't paying attention to the speed; was watching the trucks turn signals and front wheels for any erratic lane changes (they were all doing about 74 when I went for the pass). Just happened to look down at the digial speed when I cleared the last truck (can't see the analog needle from my seat position) and (in this order) : felt my sphincter tighten, gulp, whoops, foot off the right pedal, looked around for flashing lights, looked up for low flying aircraft (we are talking about Bumblebee where the top is nary up), moved over the right lane, breathe. All of which took about two seconds......
In retrospect my impression was that speed is a non entity in these P-cars. They could run in the 150's all day long and not bat an eyelash. Truly amazing machines.
I got pulled over at 122 passing trucks once. 🤦🏽‍♀️ Got a ticket for 10 over but said actual speed still on ticket. The next thread should be “fastest you have been pulled over and not gone to jail.” 😆 that would be mine. My husband got pulled over (and we got it on video) at 149 . I thought we were videoing him going to jail but he didn’t even get a ticket. It was a 65 zone at 2am empty hwy. It was a young kid Nevada hwy patrol running silent no radar on and we blew by him. He said he has a 760 hp Caddilac CTS-V so he gets it but he said slow down guys. 🙏🏻 That one was a close call we had just put in my first tune.
 

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Discussion Starter · #38 ·
I got pulled over at 122 passing trucks once. 🤦🏽‍♀️ Got a ticket for 10 over but said actual speed still on ticket. The next thread should be “fastest you have been pulled over and not gone to jail.” 😆 that would be mine. My husband got pulled over (and we got it on video) at 149 . I thought we were videoing him going to jail but he didn’t even get a ticket. It was a 65 zone at 2am empty hwy. It was a young kid Nevada hwy patrol running silent no radar on and we blew by him. He said he has a 760 hp Caddilac CTS-V so he gets it but he said slow down guys. 🙏🏻 That one was a close call we had just put in my first tune.
Oh ya and swear!! my husband said “you drive safe too” and then gave NVHP a fist bump. 🤦🏽‍♀️
 

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Cayman, about 125. Where I live it is hard to hit real high speeds without be a danger to oneself and others let alone the risk of going to jail. In Germany outside of Freiburg I hit 176 in a 991.2 GTS. I agree, once you hit 150 the sense of speed really kicks in and any imperfection in the road will make you pucker up.Cruising at 120 to 140 is comfortable. Rentals I’ve had in Germany get scary at about 120. Being closer to the cars limit makes it scary and at that speed you tend to get lift. Good aero at that speed is your friend.
 

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Nothing beats the feeling right? The rush of knowing you may be living your last moments. Wether dead or in jail. 🤷🏽‍♀️😂
This might sound od, but nope.
Been driving in Germany alot with crusing speed at 250km/h so i guess i am used to it.
And in Sweden late evenings it tends to go fast to :)

The fact that i trust my self and the cars performance shows when people want to race on the motorway.
Most people let go at 250 and no one have followed beyond 270 as of yet.
 
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