I just picked up a red SL (hand shakily writing a check), and I paid 2.9% state tax, 0.8% county tax (Boulder), 3.5% city tax (Louisville), and 1.1% RTD tax. That's just over $3k in taxes.
BTW, had a great experience working with Chris at Valley Nissan in Longmont. They have 2 orphan SLs...