Hardly news, all speedo's are out by 10%, but always the right way i.e. shows a faster speed than you are actually doing.
My A4's is almost bang on according to my RA2, as I run 18" wheels which add about 1.5% to the rolling radius, 100 on speedo = 98 on RA2.
He's got it wrong anyway as at 40k service he'll have actually done 36k miles, not 44k miles.