Can anybody suggest me chepeast car rental company for travelling to US from Toronto during weekends. Thanks a lot in advance.

You have to be careful with rental cars crossing into US.
It's not just a matter of cheapest agency in this case, but which ones allow it.
Not all agencies allow it and not all branches of the same agency do.
Most airport locations will allow you to do that but smaller suburbian branches don't.
Call your local Enterprise, Avis and Hertz locations.
Also try Discount, but very few of their locations allow it.
I know for sure that National and Enterprise allow cross border rentals.

Also, you have to book at least a week before so that they can notify the border security agency about the car coming through.

Call the agencies and find out their procedures and then book the cheapest one.

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