Let's agree: all around the best way to haul a TI is on a trailer. The TI is a beast off the ground or out of the water, so close to the ground on wheels is always the best option. Most vehicles properly equipped to tow can pull a TI on a trailer. But there is an option.
I was so taken with the TI I bought one before I figured out how to transport it. I wanted to car-top. I didn't want to pull a light trailer and don't have room to store one, so here's what I learned:
I started with a Volvo 850 wagon with factory racks (Thule). Stack the amas on top of the boat and it was a neat package. However, it was too much vertical weight for the car. Could be done, but I wouldn't tour with it. (p.s., I have no trouble with my AI on the same rig, the TI is just too heavy).
I upgraded to a truck and for a year now I've been travelling with my TI riding on top of a Tundra with Rack-It lumber racks. The rack evenly distrbutes the weight on the chassis, and you'd hardly know you have the boat on there. I carry the boat, amas and sail on the rack. I've even carried the TI and another boat. No sweat. Room for people, gear, boats, add 4wd and you got a go anywhere boat-hauler that you can park.
In the interest of full disclosure, the effort you save by not pulling the TI will get made up (and more) when you arrive and have to get the boat on and off the truck. Truck-racking a TI can hurt you if you're not careful, but with due respect and some tools and tricks it's safe and easy for an average person. Typically it takes me about 25 minutes to unload, rig and get on the water, and about 15 minutes longer to load because I wash the saltwater off the boat and dry it before I rack it over the truck.
I figure I make up the trailer difference by driving faster