Yup, you'll need to export the car from the US first, they say you have to wait 72 hours to cross back in to Canada but you don't. Then keep the documents in your car. Once that's finished, begin the import process on the Canadian side, and once again keep the documentation in your car. I did this for a couple months to prevent hassle. In the meantime, apply for your Nexus card, it's good for 5 years, and on those days when they have delays at the border, or there's only one lane open and a bunch of cars waiting, the Nexus lane will also be open and will save you a ton of time. You may need to modify your car slightly to finish the import process. In my case, I needed daytime running lights installed, which cost me about CAD$240 for the parts and labor. Take it to Canadian Tire, they're a lot less likely to try to rip you off for the modifications than some of the smaller shops that are authorized to do the modifications.
I think I paid CAD$295 all together to import the car, and didn't have to pay any import duties since I already owned the car, and included it on my "items to follow" list. Which province are you importing to?