It really depends on how you pack and what stroller you have. If you have a small 'umbrella' stroller, and each person basically has a small suitcase, you might make it work in the intermediate SUV (Edge or similar). Any sedan is likely out of the question. And if your stroller is larger than an umbrella stroller, a mid-size SUV is also likely out of the question. If there are 3 adults, the 3rd will be miserable in the back with 2 car seats. Also, car seats from rental cars (and airlines) seem to be "one size fits all" and appear very poor quality. We've been forced to use these a few times when airlines damaged/delayed our bags, and we hated them, but made do.

If you're going to do any significant amount of driving, I highly suggest opting for a larger vehicle (minivan is best, but larger/3-row SUVs could also work). Not trying to be so negative, but 5 people (including 2 car seats) with lots of luggage is VERY challenging in anything with 2 rows of seats.