Here is the Florida DMV website:
http://www.flhsmv.gov/
From the new residents area:
http://www.flhsmv.gov/dhsmv/newflres.html
Sales Tax Information for Motor Vehicles
You bought it more than six months ago
If the motor vehicle was purchased six months or more before being brought into Florida, Florida sales or use tax or local discretionary sales surtax do not apply. You'll need to show proof that you used it for six months or more in another state or jurisdiction.
You bought it less than six months ago
If the motor vehicle was purchased and used less than six months in another state, territory of the United States or the District of Columbia, the full amount of the six percent Florida sales or use tax and local discretionary sales surtax is required. However, that is offset by the sales tax you paid in the prior jurisdiction. For example, if you owe 6% to Florida, but you paid 4% to another state, you will only owe 2% to Florida.
Also check the fees - there is a $225 registration fee for each vehicle.
Hope this helps.
Z