I lived on the "rock" for about 14 years off and on while in the army.
Since then I've been back about a year ago to see my first grandchild. We drove in our 2013 Edge from Ontario.
My son want us to stay longer and use the MH, but honestly I think it is too expensive unless you are staying several weeks. If you only allocate a week I think the car rental is the best bet. Book well in advance as during summer the cars are limited.
It is a very beautiful place to visit but very expensive to live. The cost of a liter of gas went up almost 20 cents recently plus an additional tax was just added so it will be around $1.30 a liter.
So converting to US gallons you will pay around $4.90 CAD a gallon.
I would still go as the scenery etc is worth it and the people are very friendly.
(I should know, I married one