My sister-in-law has recently immigrated from India, and living with her other sister and family in Toronto. She will recently start with a new job, and it requires travelling from Mississuaga to all over the Metro area. The 2 family cars are already fully utilized; so she can not really borrow either one of them.

I have an old car that I will likely be able to give to her, when I buy a new car (possibly in the next month or two). In the meantime, she needs to most economical form of practical transportation in the metro Toronto area, which practically means that public transit/transport is out (unless she wants to be commuting each way for several hours a day to and from work, as well as between 2 or more different job locations on the same day (note- the job locations are generally well away from the TTC subway lines)).

The question is what is the most economical way to obtain a car for 1 or 2 months - renting a car from a car rental agency, for a car dealership (new or used?), or through some other process?