Comparing vs my other vehicles and using GPS / measured miles on highway markers I find my T100 reads 'high' by as much as 4% vs actual. I have factory 31" tires.

No way 30% - 70% is possible unless he has itty bitty wheels on the thing.

Sure smells like a used car dealer's pitchline . . .

Jeff
96 T100 SR5 4WD Ext Cab, Warn Hubs, HD torsion bars, Bilsteins, Camper Shell, TJM bar, factory 31 x 10.5's, Powertrax No-slip rear, Recaro driver's bucket