Last post on Feb 19, 2008 at 6:32 PM
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Chevrolet Aveo, Transmission, Sedan
#1 of 14 How can I tell if my speedometer is correct?
Feb 17, 2008 (7:05 pm)
I have one of those radar signs in my neighborhood that tells you how fast you are going. On my old car, the sign said what was close to what my speedometer said, but on my Aveo, it reads lower, sometimes substantially lower. However, the odometer is spot on correct. I know in older cars the two were related and if the odometer was correct, then the speedometer is correct. Is that still the case?
Also does having an all-white car have any effect on radar or on these signs?
I like to drive the speed limit and I can't tell if I'm going any faster or slower than usual because 99% of the other drivers fly by me anyway. I have found that if I drive the same speeds as always, I arrive at about the same time as the old car, or just a little bit sooner.
#2 of 14 stopwatch
Feb 17, 2008 (8:27 pm)
Get on the highway and use a stopwatch. Time yourself from mile marker to mile marker. 60 MPH should be exactly 1 minute. I believe 65 MPH is about 55 seconds. 70 MPH should be 51 seconds or so. 55 MPH should be about 65 seconds. On surface streets, if you can avoid stoplights/signs, 45 MPH should be 80 seconds even. 35 MPH should be 102 seconds (1 min. 42 seconds).
The color of the car has absolutely no bearing on radar... unless you managed to get your hands on some of that cool radar absorbing/deflecting military stealth paint.
#3 of 14 Re: How can I tell if my speedometer is correct? [luckins]
Feb 17, 2008 (11:46 pm)
I figured out the first couple of days that the speedometer was off. Comparing to radar signs, the speedo reads 5 mph over in the 50-65 mph range and 3-5 mph over around town at lower speeds. I compensate by allowing a higher reading than what I want to actually be traveling.
Have also checked against mile markers over a considerable distance, and the odometer reads high by 4-5%.
Feb 18, 2008 (7:12 am)
Thanks for replying.
I will try the stopwatch thing, but I don't like looking at a stopwatch while driving as I live in a very high traffic area. But, I plan to take a long trip out to the desert and there are some places where I might be able to do that. I'll take the numbers you posted with me.
I found some research that says that most speedometers on American cars tend to read as much as 4% higher than the actual speed. But, in my case, it read up to 20% off, though it does seem to be improving. Yesterday, the sign seem to indicate that it was around 10% off. The odometer is perfect, right on the mark, so I'm not worried about mileage.
The car was an ugly duckling on the lot that I got it from. It was driven heavily for the first few years, then dropped off at a dealership, and basically only driven for 20 miles during the last few months. It also rained heavily during that time and there were several problems by the time that I test drove it. But, a lot of them have resolved themselves just by regular driving and a little TLC. Maybe this will be one of those problems that will resolve itself. I just hope that if there is a problem, I can convince the dealer to fix it.
#5 of 14 Re: Thanks [luckins]
Feb 18, 2008 (3:42 pm)
I don't know why there is such a problem with speedometers reading high. Of the last 4 cars I've driven, 3 had speedometers that were inaccurate.
This isn't exactly a high-tech dilemma. It's probably just a little plastic gear that needs to be the right size, so what's the problem?
Feb 18, 2008 (5:58 pm)
Yeah, I hear that some of them are also just a magnetic connection between the dashboard and the cable to the transmission or wheels, too. But, that's what several studies have said, I don't remember the exact places, but it was several.
I know that my last 2 cars that I've owned had very accurate speedometers, too. In fact, I was "paced" by a motor officer when I had a Ford Granada and when I went 1 mile over the speed limit before he waved me to slow down.
I just noticed, today, that my local freeways don't have mile markers on them. I have to go way out of town before I start seeing them.
Feb 19, 2008 (7:40 am)
I just found out that there is a TSB relating to incorrect speedometers on the year and model that I have. I am taking the car in for a timing belt change in a couple of months, and will bring this up to the dealer. Hopefully, having a TSB number or copy of the TSB will convince them something needs to be done if it's really is inaccurate. I will let everyone know how the road test went when I can do it. It's not a major thing, but I like my speedo to be correct as possible.
#8 of 14 Re: TSB [luckins]
Feb 19, 2008 (11:03 am)
What year is your car and does the TSB include every vehicle in that model year?
Feb 19, 2008 (11:29 am)
The NHTSA number is 10018606 and seems to cover all models. I have a 2004, but it seems to cover up to 2006. I haven't been able to find out all the details, yet, but I'll dig around. It seems to be a recent TSB. I also get a number 3774, I think, too. The problem is that you have to pay to get the full reports.
#10 of 14 Re: TSB [luckins]
Feb 19, 2008 (12:16 pm)
Thanks. Went through the entire list of TSB reports for my model year. Almost all the issues I've had are addressed, but the dealers have been unable or reluctant to fix the problems.
Doesn't matter to me now as its got high mileage and was restyled by a snow plow in December. The inevitable progression from shiny new car to beater.