Mounting 3d party GPS
 

Hi,

I recently bought a Garmin GPS and have been pleasantly surprised:

• Accurate speed and distance measurements
• Alternate, fuel efficient routes
• "Where did I park the car?"
• How to get there from here
• Car manufacturer GPS are often not as good as COTS units

If you have an off-axis instrument cluster like a Prius or Echo, this approach makes it easy to mount the GPS where it doesn't block the driver's view; is easy to operate; yet provides full functionality:
http://hiwaay.net/~bzwilson/prius/pri_gps_010.jpg

Bob Wilson

Why not mount on windshield? Not saying you should, just curious why you chose not to...

Hey Bob, what model is that? I got a Nuvi 250W last month and it looks exactly the same :) I'd love to mount mine somewhere other than the window, but that will wait.
You said your's has a fuel efficient route option? Mine only has fastest and shortest. The latter can take you straight off the highway and into someone's driveway and through their yard, so I input the fast route, but go my own way when I know a shortcut.

My parental unit puts hers in the windshield. It blocks so much of the view that I have to take it down whenever I drive.

alot of states do not allow anything to be mounted to the windshild, or to hang in front of it, fuzzy dice are illeagle to hang from the rear veiw mirror.

I know it used to be in CA, so I used to mount it in the drivers window at the very front corner where all it obstructed was the base of my mirror, and a little of the body :)

Now I think CA lets you mount a GPS in a 5x5 inch square on the drivers side corner of the windshield, so now I mount it there...

Both the Prius and Echo have the speedometer and displays located in the center of the dash, between the driver and front passenger. So the area in front of the steering wheel is available and easily reached. However a ham posted this photo of his instrumentation setup and now I'm designing proper instrumentation mount:
http://www.aprs.org/prius/photos/Dash-best-xx.JPG

But I wanted to share something I found with the Garvin nuvi. When mounted as a USB drive, there is a file:

GARMIN\GPX\Current.gpx

A text XML file, it includes not only way-points but also a history of your driving. Using an excel hack, I was able to parse the trace and overlay it with a Google Map:
http://hiwaay.net/~bzwilson/prius/pri_gps_100.jpg
Within the limits of a quick hack, the graph traces exactly the route I drove that day.

I then went to my favorite 'flat tracks' and set way points:

• Coast 01
• Coast 02
• Coast 03
• ...

This will significantly improve the data capture quality as well as make it easy to characterize the performance of other vehicles. Yes, there is the problem of GPS 'wander' but the same problem exists with manual data capture. The solution is multiple runs and averaging out the error.

One other thing, my Prius does not have a way to adjust the calibration of the speedometer. But the GPS speed and trip duration matches exactly the calculated tire diameter difference. I am seriously thinking of blocking the existing speedometer with electrician's tape and using just the GPS indicated speed. But when I record my mileage, I'll still adjust the distance per the difference between the GPS and tripmeter.

Bob Wilson

Hi,

Any permanent mount puts you at a very high risk of having someone smash your window and grab the unit! Right here in our parking lot at work, we have had 3 or 4 GPS units stolen during the day, while we were all here! I'm told that even the circle mark from the suction cup on the windshield is enough to get tempt a thief.

The best method I' ve come across is to use a "beanbag" weighted base on the dash -- and always, always, always remove the unit and the base.

I have been thinking of enabling the password access. But the next instrument mount will be more subtle to anyone wandering by the car.

Bob Wilson