Thanks everyone who contributed to this thread. I just discovered the speedo error on my '03 1150GS Sport, when comparing GPS to speedo. I was a little shocked to see that to ride at a steady 55 mph, I had to get the speedo up to about 68. As I recall, I came up with a 19% error.
I submitted a thread to the bmwmoa forum under oilheads, and finally someone directed me to this thread, which has been most informative.
After some negotiation, one of the shops has agreed to replace the speedometer under warrantee. However, they were silent on the drive hub change. Since I probably won't be running Tourances, I think the "2.9" drive will be excellent, once I get a reasonably accurage speedo, and I'll get one on order.
My suggestion on the moa forum was for riders in the USA to send notes about defects they consider to be safety related to NHTSA, so that if there is a trend, NHSTA might order the manufacturer to come up with a fix. Once NHTSA issues an order, the company has no choice but to develop a fix that is acceptable to NHTSA, and then issue a recall.
My feeling is that on a machine as expensive as a BMW, a critical item such as the speedometer should be reasonably accurate. I would define "reasonable" as "within 5% as delivered with stock components". I know that a motorcycle manufacturer can have a speedo that reads up to 10% faster than actual, but here's an issue where BMW should use it's mighty technology to do better than the minimums to justify the healthy price tag. If you bought an inaccurate Rolex, would you put up with sticking little dots on the dial to represent "real" time?
Is an inaccurate speedometer a safety hazard? I think it is. If you believe a speedo that is say 10% optimistic, and you're trying to avoid a ticket, you would be riding 10% slower than traffic. And I think that would be hazardous. If you also believe that an inaccurate speedo is a safety hazard, (or if you're just pissed that BMW is so arrogant about the whole deal) consider sending a note with your speedo error experience to Bob Young, NHTSA office of Defect Investigations, firstname.lastname@example.org
It seems to me that if owners can buy a stock BMW part to get the speedo closer to reality, BMW could supply new machines with that same part and save us all the trouble.