GPS speedometer

[MarkM66]

I think I remember seeing this item in a magazine. It's a gps speedometer that you could just plug into your cigarette lighter.



Anyone know of such a thing?

[CarlC]

There are handheld GPS units available that have speed capability. The last time I looked they were in the $800 range.

[TonyL]

Almost ALL handheld GPS units work for MPH. I have a Garmin etrex legend. 150 bucks at REI. (200 at target) there are cheaper ones, but Im an avid Geocacher, so the features on mine are needed.

[CamaroAJ]

in the new Boating World mag they have the speedo that is done 100% GPS. it would work in a car and you would know how many knots your land yaut (sp?) is going

[MCMLXIX]

Bringing up a 5 YEAR OLD thread because "I USED THE SEARCH BUTTON" and found a topic with the perfect title .... lol

Anyway. With 5 years of progress and advancement in technology... How many people are using one? I just found a speedo I like and they offer a GPS version....
http://www.speedhut.com/gauge_produc...ometer_GPS.htm

How accurate are they really?
Does the GPS signal ever disappear or black out?
Anyone running gauges from Speedhut (GPS or Not)??

[Jim Nilsen]

I have a Racepak and the gps works well and it has the anntena mounted under my rear spoiler. i also have a Stewart Warner 200mph speedometer in the middle of my dash. You might ask why?

In the wondeful state of Ill. you have to have an odometer and the Racepak will sometimes lose the odometer info from what everyone has seemed to experience. The odometer on the SW will also make my insurance man a bit happier when he wants to be sure how many miles I go. It would be no problem I would think if I lost the odometer info from the racepac or the SW but I just wanted to comlply. I have also had a few times the gps was not able to get a signal and the SW was there for me. The SW also sometimes read high and other times low for whatever reasons, not by much but it is off sometimes from the Racepak gps speed.

If you deduct the cost of things like gps,total data aquisistion, lap times, left and right g forces ,accelerometer for braking and acceleration, and a host of other items and deduct the seperate cost of units from the actual cost of the Racepak you actually get the most number of gauges for the same or less cost of most any other totally complete gauge package from anywhere else.

I went over my original budget to get the Racepak vs the Autometer Nexus gauges that never came to fruition and now am glad I did.

Get the right gps and it will give you so much more than just speed and how to get there.

[wmhjr]

GPS speedos are neat gadgets. They are not as accurate as mechanical (also meaning electric signalled mechanical speedos). A GPS speedo will always lag. If it has at least 4 strong sat signals on level ground, it will be OK. If there is elevation change involved it'll be much less accurate.

Jim, I'd be willing to bet that your SW speedo is right on, and your Racepak is off - a little high sometimes and a little low other times. Look at the math of it. The SW cannot be both high and low. I'm assuming it's driven off your tranny, right? That means it's a very simple mechanical formula where shaft revolutions are converted to displayed speed. It may be off - but it'll always then be off in the direction - either high or low. By a static variable.

A GPS, OTOH, takes satellite signals, calculates the time for that specific sat signal to reach the gps, knows the location of that sat , and compares that to the same data coming from other sats. It takes 3 sat signals to get a 2D fix, and at least 4 sat signals to get a poor 3d fix. It's constantly calculating all those vectors. Sat signals are constantly falling in and out. Then you have the sat altitude, all combining to result in something called DOP (dilution of precision). It varies by location and time of day to to these factors.

Bottom line is that unless you live in the desert, a GPS speedo is simply not an accurate instrument. I'm not saying that the Racepak isn't a good item. Just that the GPS speedo idea is not and probably will never be a recommended solution for cars.

[avewhtboy]

I found a free app for my iphone that is a speedometer and distance traveled readout.

[John Wright]

I like those Speedhut Revolution guages...