In general there is one main question to answer in importing a car: Is it less than or more than 15 years old. The rules change depending on which it is.
If under 15 years old, go to the RIV Canada website. Rules are there.
If it is over 15 years old, the rules are very few. US Customs will want to see the paperwork before exporting. Canada Customs wants to see the paperwork at time of importing. Federal sales tax is based on selling price and I believe payable at the border crossing. The majority of our provinces will require an out of province inspection before you can get the car insured / registered / titled to drive on the roads up here - depending on the work, this can be expensive. This is not part of the RIV process and you are not mandated to take it to Canadian Tire for the inspection. Interesting thing about the RIV site, if they do not discuss something or there site it essentially means that you do not need to do it.
Once the inspections are done, you will need to pay provincial sales tax (if applicable) at the time of vehicle registration in Canada.
The most comprehensive site I have come across for details / explanations / help / instructions in importing a car is from the Pelican Parts Porsche forum:
https://forums.pelicanparts.com/canada/288322-importing-porsche-us-into-canada.html
One other note, if you import a car and declare it as 'parts' it may be the kiss of death for that VIN. It can be a very money and time consuming process to get the car legit. Advice is to import it as a whole car, you are saving nickles and in the long run it will cost you dollars.
Will you pay duty? Maybe, maybe not. Some have had success with claiming it is an antique. Sometimes the border agents are Ok with that argument, sometimes not. To save headaches, plan on paying it and if the agent does not ask you to pay it then BONUS. If you do pay for it, make your claims after you are back home and not when you are at the border.
I believe (and others, correct me when I am wrong) that all US states have vehicle titles - proving vehicle ownership. Not sure about Manitoba, but here in Alberta we do not have titles for the car. We have registration, which can be used for ownership but its main intent is that the car is legally allowed to be drove on public roads. We can buy / sell cars with only a Bill of Sale. How do you go about buying / selling cars in Manitoba? The process may not be different, even tho there is an international border - but check with them first.