PDR Speed Accuracy?

Tim M · 08-18-2019, 07:25 AM

I've got a 2018 Camaro SS 1LE with PDR on OEM tires.

Curious if anyone can confirm the accuracy of the speed on the PDR recording - ie compared to GPS?

I believe the speed is pulled from the VSS as I've gotten wheel spin/skip on bumps and the speed jumps up accordingly - see recent ring lap with multiple 'hops'.

I know my C4 Corvette speedo was quite accurate even at high speeds, but typically cars (especially European models) have a ~3-4 mph conservative error. My experience on older motorcycles was simply a percentage error - ie 139 MPH indicated equaled a real MPH of 125.

Bottomline: how accurate is the PDR?

Thanks.

Camarentino · 08-18-2019, 03:59 PM

It's a little off both mph and time. At the track my pdr showed 13.09 @ 115 but track time slip says 12.91@113. It's a good tool to have but it's not 100% accurate

beedo · 08-19-2019, 05:33 AM

Mine is dead on within .5 MPH, I have a uniden R3 radar detector that displays GPS speed and the are usually the same give or take maybe .5 mph

wnta1ss · 08-19-2019, 05:53 AM

There was a PDR video of an SS/1LE running on a speed track posted, and the speed reported on the PDR was 174. The timed speed was 172, so it looks like the speedometer is very slightly optimistic on that 1LE.

Gary H · 08-19-2019, 07:39 AM

If the difference at 172 is 2mph, that works out at just over 1%, which I would say is pretty much as spot on as you can get!

Tim M · 08-19-2019, 07:45 PM

Appreciate the replies.

I'm curious at the high speed accuracy.

For quarter mile: believe most tracks use an average of a short distance at the end of the quarter mile rather than a snapshot speed like the PDR gives.

I would imagine tire wear and pressure will play a part too.

Likely I will just buy a GPS to verify, if I'm curious.

Scargoes · 08-19-2019, 07:59 PM

Federal motor vehicles standards are vague but give about a 5% error to manufacturers above or 2% below, EU does not allow any below % thats why they all read high. But Car and Driver had a story back in 2002 that revealed that in their testing of all domestic makes, GM had the most accurate https://www.caranddriver.com/feature...meter-scandal/

That being said, the gps speed displayed on my phone is within 1mph of my headsup display, and thus the PDR display, every time I've checked it.

wnta1ss · 08-20-2019, 06:37 AM

Quote:

Originally Posted by Tim M

Appreciate the replies.

I'm curious at the high speed accuracy.

For quarter mile: believe most tracks use an average of a short distance at the end of the quarter mile rather than a snapshot speed like the PDR gives.

I would imagine tire wear and pressure will play a part too.

Likely I will just buy a GPS to verify, if I'm curious.

That PDR video that I was referencing was not far off as far as percentage goes.

1/4 mile dragstrips these days get speed from the average of the last 66' of the run. The 2.7 mile run that video was from probably averages the last 132' of the run.

Timbo-1LE · 08-23-2019, 02:59 PM

PDR said 174, this was official timing just under 173, pretty close...

08-18-2019, 07:25 AM	#1
Tim M Drives: 2018 Camaro SS 1LE Join Date: Jul 2018 Location: Stuttgart, Germany Posts: 807	PDR Speed Accuracy? I've got a 2018 Camaro SS 1LE with PDR on OEM tires. Curious if anyone can confirm the accuracy of the speed on the PDR recording - ie compared to GPS? I believe the speed is pulled from the VSS as I've gotten wheel spin/skip on bumps and the speed jumps up accordingly - see recent ring lap with multiple 'hops'. I know my C4 Corvette speedo was quite accurate even at high speeds, but typically cars (especially European models) have a ~3-4 mph conservative error. My experience on older motorcycles was simply a percentage error - ie 139 MPH indicated equaled a real MPH of 125. Bottomline: how accurate is the PDR? Thanks. __________________ 2018 SS 1LE German Based Nurburgring Visit #19 Ring Laps: 77

08-18-2019, 03:59 PM	#2
Camarentino Drives: 2018 Camaro 1SS 1LE Join Date: Dec 2017 Location: Toronto, CAN Posts: 210	It's a little off both mph and time. At the track my pdr showed 13.09 @ 115 but track time slip says 12.91@113. It's a good tool to have but it's not 100% accurate __________________ 2018 Camaro 1SS 1LE w/PDR Summit White KN intake-MBRP cb- 2nd cat deletes- ACS sides- iroc Z spoiler- Eibach Pro- Katech 95TB- MSD Manifold-GM strut bar- Custom tune by Arun Ahuja @ CCPERF.ca

08-19-2019, 07:39 AM	#5
Gary H Drives: Camaro ZL1 Join Date: Apr 2019 Location: London, UK Posts: 304	If the difference at 172 is 2mph, that works out at just over 1%, which I would say is pretty much as spot on as you can get! __________________ Made in the USA. Refined in Great Britain - insta: zl1uk Velossa intake, Rotofab, Mamo TB, Custom ported NX Lid & Jokerz Full tilt ported LT4 charger, 3 port CoolingMist Meth injection - ATI 15% lower pulley, E2X CC, TSP ceramic coated longtubes, de-cat and Borla 60608 to NPP box, JRE tune, BMR rear control & trailing arms, lock-out kit, lowering springs and front strut brace, Custom carbon trim interior, Xpel ultimate front PPF and Prestige window tint with Chameleon Windscreen tint...ever evolving...

08-19-2019, 07:45 PM	#6
Tim M Drives: 2018 Camaro SS 1LE Join Date: Jul 2018 Location: Stuttgart, Germany Posts: 807	Appreciate the replies. I'm curious at the high speed accuracy. For quarter mile: believe most tracks use an average of a short distance at the end of the quarter mile rather than a snapshot speed like the PDR gives. I would imagine tire wear and pressure will play a part too. Likely I will just buy a GPS to verify, if I'm curious. __________________ 2018 SS 1LE German Based Nurburgring Visit #19 Ring Laps: 77

08-19-2019, 07:59 PM	#7
Scargoes Drives: 2018 Hyper Blue 2SS 1LE Join Date: Aug 2018 Location: Dessert Posts: 486	Federal motor vehicles standards are vague but give about a 5% error to manufacturers above or 2% below, EU does not allow any below % thats why they all read high. But Car and Driver had a story back in 2002 that revealed that in their testing of all domestic makes, GM had the most accurate https://www.caranddriver.com/feature...meter-scandal/ That being said, the gps speed displayed on my phone is within 1mph of my headsup display, and thus the PDR display, every time I've checked it. __________________ 2018 Hyper Blue Metallic 2SS 1LE with Nav, PDR, and track alignment 1:34.20 Willow Springs Big Track

08-19-2019, 05:33 AM	#3
beedo Drives: 18 2SS 1LE NFG Join Date: Aug 2018 Location: Mansfield Posts: 133	Mine is dead on within .5 MPH, I have a uniden R3 radar detector that displays GPS speed and the are usually the same give or take maybe .5 mph

08-19-2019, 05:53 AM	#4
wnta1ss Drives: 2017 Camaro 1SS Join Date: Aug 2016 Location: NH Posts: 1,692	There was a PDR video of an SS/1LE running on a speed track posted, and the speed reported on the PDR was 174. The timed speed was 172, so it looks like the speedometer is very slightly optimistic on that 1LE.

08-23-2019, 02:59 PM	#9
Timbo-1LE Drives: 2017 SS 1LE Join Date: Mar 2017 Location: Florida Posts: 617	PDR PDR said 174, this was official timing just under 173, pretty close... Attached Images

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