Russ, Does your speed work all the time ?  If so and the odom. is the only problem,There is no fix other than replacing the whole unit.  32 to 35 sounds about right for the heavier Jetta, colder temps, driving habits and the mileage on the car.

Russ, Does your speed work all the time ? If so and the odom. is the only problem,There is no fix other than replacing the whole unit.

If it's anything like a bug's odometer, there is a little plastic gear pressed onto a shaft inside the odometer.  There are some little grooves in the shaft that hold it tight . . . until the gear cracks.  Then the gear will slip and stop turning the odometer.  I've taken a BUNCH of them apart and fixed them.  One actually worked for .7 miles after I fixed it!  If that's what your problem is, listen to David.  Don't waste your time trying to fix it.

I don't think I've ever had this problem on a standard Beetle, but almost every Super I've had was like that.  I was looking for an early Rabbit cabrio a few years ago and noticed that almost every one of them had between 89 and 91 thousand miles.  Most of them OBVIOUSLY had more miles than that.  I'm slow . . . but after looking at about 10 of them I figured out that there might be a problem with their odometers.    :-k

Several years ago when I was first getting into Volkswagens, there was a website called the VW Archives.  There was a guy on the forums there that said he had found a brass gear that was a perfect replacement for the plastic gear on a Super Beetle odometer.  He said they only cost a few pennies each.  That web site has long since vanished . . . I don't know where he got the part or what it was intended for, but it seems like I remember he said he got it at a local hobby shop . . . maybe something to do with model railroading or model planes?  Anyway, if I could find a brass replacement gear, I'd tear back into one of the many broken ones I have . . . not that I am interested in trying to make 50 cent an hour repairing them, but I've already invested many hours working on them . . . I'd like to be able to say that I did get ONE fixed!

But I did better, 36 MPG and the odometer didn't stick, at least not that I noticed.

My theory there is the plastic gear in the odometer that is cracked is less flexible and sticks to the shaft better when it's cold.  I've noticed that Joy's convertible's odometer slips less in cold weather too.

Went 399 miles this time on 10 gallons of gas...that's right at about 40.

At this rate I should hit 100mpg by spring.