does the border patrol know how long I have been in US for

I have been in the US for a year and want to go back into Canada for a visit only came to the US with my Passport have started a life in the US and want to be able to come back however I want to know if the Border Canada and US know or have proof of how long I have been in the US for?
when I came over I came with my car so I am sure my car was registered however I will not be returning to Canada with that same car as it broke down and I had to sell it.
also I would be returning to Canada in another vehicle which I bought in the US and it is registered to myself and my BF's sister.
so wondering also how this would work as well?