Speed to change into top (5th) Gear on Tip G/Box ???

I have just updated my W210 E320 CDi Avantguard Estate from a 1999 to a 2002 Model.

Both fitted with the 5 speed Tiptronic Gearbox

On my 1999 the car would go into 5th gear at about 32 mph.

On the new one it waits until 44 mph to go into 5th.

I have carefully checked this with a fully warm engine.

Anyone think of a reason ???

Regards

Mike