Depends on the state. In Michigan its 6% on the purchase price, trade in doesn't matter...new or used doesn't matter. Its 6%.
2009 G8 GT Stryker Blue Prem/Sport/Roof
Go: Rotofab, 1 7/8 Kooks Mids, Corsa Exhaust, FE3/Pedders Suspension, a little HPT = 12.9@108 (2.03 60')
Show: V8 Holden Badges, Clear Side Markers, GXP Rear Diffuser
Misc: AutoDim Mirror, Almost Factory Bluetooth
2017 Chevrolet SS Orange Blast, A6, Stock except Holden Badges
2013 Dodge Caravan R/T - family Hauler
2002 Grand Prix GTP 40th Anniversary. SD headers, CAI...stock pulley.14.2@98 (pre-headers).