Hard to say! When I got my car 30 years ago, the speedometer would bounce up and down +/- 10 mph of the actual speed being traveled, and the odometer would register about 1.5 to 2 miles for each mile driven. Then a few years back, the odo quit altogether. Just let the speedo do it's thing - it was kind of entertaining as you were traveling down the highway; speed didn't matter, because we were never going faster than anybody anyway, and it just seemed to fit with the car's other eccentricities, so it stayed that way for 27 years. In 2002, right before her first long trip (Open Roads 2002 - Tahoe), had the speedo repaired, and since then, we've gone about 20,000 miles - Tahoe twice and Eureka, and lots of trips to the grocery store.
A friend, George Keens, original owner of his '55 BN1, has about 45,000 miles on his car.
Sharon
BN1