How much will it cost to drive from Montreal to Niagra Falls?

Here is the scenerio:

Next month we're planning a trip from Montreal to Niagra Falls. My husband is going to run the Niagra Falls marathon, so we're going for the weekend.

Our car uses about 1 gas tank (50L of gas) for approximately 600km. The distance from Montreal to Niagra falls is 667km (you could get the students to look this up as an extra challenge). Also I plan to drive around in Niagra falls a bit (at least 84km, as I have to drive my husband to the start of the Marathon, which is 42km long, and then come back to the finish line in Niagra Falls).

I estimate the price of gas to stay similar to what it is right now: $1.40/L in Montreal, but in Ontario it decreases significanly to $1.30/L (again these prices could be looked up for more exact values). Initially I would have to fuel up in Montreal, but as soon as I reach the Ontario boarder, I could get the discounted price of gas.

So with those parameters, how much will it cost me to take the trip to Niagra Falls and back - the cheapest option. For extra fun, you can include eating out every so often, hotel in Niagra Falls (for the two nights), Marathon Cost, even car depreciation due to the long trip. A fun little project, and very applicable to the real world: I just had to do these calculations myself!