Palting

Isolated 4 lane high way goes nowhere to nowhere, 5 miles. Long story regarding court case 'cuz highway goes through breeding ground of protected pre-historic mosquito or something.

Anyway, after recon run one way, came back for the speed run. This was early in my car ownership soon after the break-in period at @2500 mies on odo. Redline 1st, redline 2nd, redline 3rd, redline 4th, chickened out and short-shifted 5th to 6th. Smooth, flat, planted at 168=170 MPH on speedo before this voice in my head yelled "Are you NUTS!!!!". Haven't done it since.

RJMDAD996

168 mph - in my Targa - and 188 in my friends F430 -

lanny

154 but it always reads 5 mph higher than the road side signs- no other car I have driven does this and it has the factory wheels and tires so myabe this is just a 996 thing? I dont remember my boxster doing this.

htny

yeah the error drives me just a little nuts because it seems to scale, but if that's the biggest complaint at 170mph then it's one hell of a car.

slant911

Yeah funny thing I noticed about the error in the speedo is that when I took my run at a radared and speed trapped 171 MPH my speedo read about exactly that speed, but at regular highway speeds (ie. 80 MPH) it is always a few MPH faster than reality. I actually took 3 runs that day that ranged from 169 to 171 and every time my speedo was pretty much right on with the official results. I'm wondering if the error actually gets to be less as you get going faster.

lanny

sounds like something I should investigate

htny

for me the error actually increased with speed, but I am a little smaller than stock diameter in the rear.

By the way I did check my notes and while I had remembered as a +10 mph error at 150-170 it was +6 to +7 mph speedo vs my GPS.

Without knowing the calibration of either instrument definitively, there's no real basis for comparison. I'm more of a mind to trust the radar trap

missmy993

I saw 120 mph at Gratten. '99 C4, 84K miles

MagnusB

125mph at Thunderhill.

jorj7

As the speed increases the diameter of the tires increase. At 170 you can get
2-3% more mph per rpm...

ps. I've had my 928 up to 190 on the GPS and hope to do a lot better this summer
with a 100 extra rwph

photo25

Just testing my2004 GT3 in Conn early AM RTE 84 no traffic saw 165MPH, and that was uphill. Stable as a rock and didn't want to end up in Jail so backed off at the top of the hill. Had plenty more RPM to Go !
Think I'll wait for track time in the future.

GoodSpeed Sweden

280 km/h (175 mph) on the speedo on a German Autobahn last summer

judd944

105 maybe 110 at Nelson Ledges, OH.....in my 944

Orient Express

165-168 on 101 south of Soledad. 5 miles of straight highway.

10 GT3

On track, 140+ on the front straight at TWS. On street, 165 mph on a river causeway with a side wind (didn't feel safe going faster).