Vehicle Inventory Tax(VIT) is assessed based on sales price of vehicle.
Same as sales tax. Sales tax is collected from the purchaser at time of sale,
and paid to the County Courthouse when title is processed.
All sales are reported monthly, on a separate form, with selling price.
VIT is paid by the dealer to the County at this time.
Late filing of these monthly reports carries massive fine($100/day).
The rate is recalculated once a year.
Ours is currently .0016xxxx(it's taped to my monitor at work). Works out to about $30 in a $15,000 motorcycle.
I know of no difference in the tax between cars and m/cs.

We charge it as a separate line item on the invoice, along with
state inspection, registration, and sales tax.

The dealer could not charge you the sales tax as well.
He won't be at it for long, though.

__________________
Todd Haven
Parts Manager
MPH Automotive
Houston,TX