I purchased my '99 TL in Dec '06 with 60K on it. Just bought some new Yokohama P205/60/16's AVID H4S's to replace the original(?) Michelins. Took a road trip from S. Florida to N. Georgia last week and love the new rubber, quieter and better handling.

My question is this: Has anyone seen a big difference between the speedo speed and actual speed on their TL? I took my boat's GPS which gives speed over the ground and it was consistantly 3-5 MPH lower than what the speedo was showing. This was at between 75 and 85 MPH on level surfaces with the cruise control on. By compairson, my old Benz was dead on, speed wise, under similar conditions.

I initially thought this might be due to the new tires, but the diameter difference is .5% and the speed difference is 3-3.5%. I did not check on the speed difference with the old tires.

The good news is that I am getting good mileage, and drive slower than I think I am. The bad news is that I am not getting the great mileage I think I am, and I'm putting more miles on than actual. My "adjusted/estimated" MPG was 27.5+ from Lauderdale to Jaxonville, on fairly flat roads with the AC on.

Any thoughts? Are these speedo's adjustable, and how?

 

I am still using the stock size tire, and my speedo is dead on with my TomTom GPS unit. Maybe you can borrow someone else's GPS and see if it is still off?

 

3-5 lower does sound a little high but if you read caranddrivers review of there long term test BMW 330i it did the same thing. I heard speedomotors are normally 1-3 MPH fast for legal reasons however I am not sure what the case is for the TL.

 

Wasn't this the point of a class action lawsuit I read about somewhere on this forum?
I think you warranty has been extended by a little as a result.

 

That only applied to 02-06 Acuras.

 

My GPS is accurate, I think it's the speedo, but I may just be a bit anal about this difference.