Want to rent a car for 6 months to tour France, Spain, Portugal

I'm a Canadian planning a 6 month trip to Europe this fall and would like to rent a car for 6 months to tour France, Spain and Portugal.  I know it's not cheap but hoping there may be some good advice on how to approach this and whether or not it's even practical?

Do European car rental companies permit inter-country travel?
Can you recommend a rental company that is better for rates or otherwise?
Thanks, Les

Rent in the country with the lowest VAT. Try Luxumburg

Do not rent. Do a lease-buy back from one of the companies that do that. Years ago Peugeot and Citroen did it. The company name was Sodexa near Paris for Peugeot. I did it with both companies. A froends still does it every year. Gets a new Peugeot each time. Check online for lease or lease-buy back Europe.