85 MPH - It just can't be.
 

On highways with 65 mph speed limit, I frequently find myself amazed at how fast I am going all the time. I look down and see that I have to hit 85 mph to slowly pass centerlane cars. This means that they are all doing around 80, which I am having a hard time believing. To me it feels like I am only doing around 70 at a reading of 85, this is way off. Is it just me or does anyone else notice this. It could be that the speedo is not calibrated, or it could be just my perception. Also, It could be that the speedo is calibrated for the stock 16 wheels regardless if the car gets C7, which I have.

I'm pretty sure I read somewhere where that up to 5 or maybe even 10 mph is an allowable deviance by law. Any suggestions on how to test the speedo accuracy? At 35 mph it is pretty close (based on those radar speed reminders that police put up in school zones) but the variance does get greater as speed increases.

The C7 is almost spot on w/ the stock set. You are going that fast! Remember cars are greatly improved over the past 10 years and fast then does not feel fast in a modern car. Even good older cars are a lot less rigid than a lesser new one, so they dont have that 'I'm going really fast feel'.

To check the accuracy of your speedometer, go onto an flat portion an Interstate or the Turnpike and set the cruise control to 60mph. Use a watch or stopwatch to time the mile marker posts. Time 5 or miles and take the average.

sometimes I found myself passing cars on the freeway at 90-95 mph and I didn't realized it. I guess it doesn't take long for it to go from 70-95.

I actually had my wife follow me to make sure that the speedo was correct. The coupe is so damn quiet and stable that 85 feels like 60 in a lesser car. When you're on the highway it's quite easy to accellerate to 85 or 90 in just a couple of seconds.

Here in Orlando average traffic speed is 75, on a posted 55. If you go 80, you 's-l-o-w-l-y' pass the average traffic. Cops are cool though and really look out for the sole-gunman speeding past average traffic, making going 80 pretty safe.

Lucky... Here in DC area they'll pull you over for just over 70...

And yes, I also noticed that perception of speed in the Coupe is "non-linear", so to speak. It feels rather fast at 40mph, but doesn't feel too fast at 85, feels just "right" :) Which makes perfect sense - German cars are meant to be driven fast and are designed that way.

So when my spedo hit 129 mph last week :D (I had to try it...long, straight and open freeway in the desert) I can tell my wife it's the wheels!

I like!

Btw, 129 scared the ***T out of me! Big difference from the Jammed 405!

remind me never to race a C230 on the highway... my Z3 shuts you off at 128m its pretty abrupt... you're accelerating fairly rapidly (for that speed) and then suddenly, you're not accelerating any more... just stuck at 128. man, I need a chip.

back on-topic, if 85 feels like 60, its probably just the car being that much smoother and quieter. I am very guilty of going 80 in the Z3 when I assumed I was going 65 or so, just due to the sound levels.

I know what you mean
 

You need to see the look on my face everytime I look down and see the speedo at 100! It has happened more than once. But I dont think anything is wrong.... Im just flyin. The road is usually pretty empty but I rarely if ever see anyone passing me.

Measured Mile Formula
 

Howdy Folks:
This is the formula for average speed over a measured mile:
average speed(mph)=3600 divided by the number of seconds it took to go the measured mile. It helps to time the start and finish from the the same point on the car. (I use the passenger A pillar)

Talkin about your Z3, I used to have a 95 3 series BMW, the speed limiter sucks so I was on a very steep hill and I put it in neutral after I hit the limiter. After going a few miles past the limiter due to the momentium the engine shut off on me. Still had power steering and brakes which shut off as I came down to 80mph, then I just turned my key and started everything up. I havent tried this on my MB but I really dont want to either... Very scary experience...

that's ODD:eek:

I had a 95 318i automatic and i got it to go about 5kmh over the speed limiter.. which was about 187kmh. I hit it out of momentum i guess.. going downhill.. but after that, just no power, but not a TOTAL engine shutoff.

I've never heard of the engine shutting off, but I suspect it had to do with the fact that it was out of gear... I can imagine the fault codes screaming through the computer...

I experienced the same thing as pokerFACE... was VERY predictable! (thats good)... when I can afford the $1000 to move up to 17-inch wheels and a good set of michelin Pilot Sports, I'll get a chip to conveniently remove that limiter... I just wish they made a chip that was only compliant in the lase faire agricultural midwest... none of this 50-state stuff, as long as its legal in Nebraska, its good with me!

It seems that with all the refinements to the cars, you seem isolated from the road....you cant tell if you are going that fast since everything is so quiet and smooth....90 seems like 60....but I tell you...I had my C240 top out at 132 and you can see real estate go by very quickly.....the car kept going (I kept up that speed for about 5 miles) and the motor did not shut down to slow down....but it is very easy to go fast and not realize it....I am always checking the speedo....

Okay, so according to shahtc,

when the w203s hit their max speed, they just *sit there, correct? no unwanted cut-offs, engine shut downs, bouncing needles, etc etc...

I've never taken mine above 165 kmh.

Well, I can't answer the question about a limiter specifically, but like I posted earlier, I've taken my coupe to 129, and I had to let up.... Mostly due to the fact that any faster, and I'm changing my shorts, or a rabbit crosses the road and I get turned into road kill. You definately notice the speed at that rate.

The car felt as if it wanted more speed too! What a ride!:D