Hello Road Trippers!

First post so thought I should ask the most challenging question first: should I really go for a rental car or go for what seems to be the cheaper option of buying a used car?

I will be traveling with two/three others on a one-way trip from San Francisco to New York over 4 to 5 weeks in Sept/Oct. The timeframe is very flexible right now, but give the amount of days, taxes, states lines, I'm leaning towards buying a used SUV...

Any thoughts are appreciated and apologies if this is repeating old info...