It sounds like you may not do much coding, so yeah there is a bit involved of course, but here is some essential details on a way to implement what you are trying to do. Unfortunately I don't have much time to help more.
The easiest way to accomplish this is to create a native app with a custom graphic component for the fancy speedometer with the Android 2D graphics API. At its simplest you could have an image provide the background for the speedometer then simply draw a line for the needle. You could also conceivably use an image for the needle and rotate the image accordingly.
If the speedometer is linear from 0 to max speed things are fairly easy to determine the rotation of the needle. Let's say it will rotate on the top half of a circle for speeds 0 to 200 km/h. 0 is PI (radians angle) and 200 km / h is 0 (radians). You can determine the point along the unit circle in screen coordinates (0, 0; upper left corner - 2D API is oriented this way) by applying x = cos(<angle in radians>); y = -sin(<angle in radians>). You can treat this (x, y) as a unit vector / normalized direction. You can multiply it by a scalar value to increase the length.
For a linear mapping of speed to angle in radians for rotation around the top half of a circle you'd calculate PI - PI * (speed / max speed).
For a review of general trig and a picture of the unit circle and how radians relate check this out:http://library.thinkquest.org/20991/alg2/trig.html