I have flown twice with my bike in a B&W International Bike Box. (bike case).
B&W Bik box
For the first i had transportation arranged as part of the cycling camp i was participating in, so that doesn't apply. the second time, we went to Maui, and i used the case again. we rented a small SUV, it was a Nissan rouge, then a ford escape. the case fit OK, but i think we had to put the seat down to get it in there (2 passengers only).
here are the additional costs associated with flying with a bike:
1) most airline will charge an additional $150 each way for the oversized cargo... Delta is free, which is why I target them is I can. (50 pound limit)
2) TSA is great at opening the bike case, but SUCKS at closing them properly. (this one is kind of hard to figure out).
3) you can rent a bike in a lot of places for $50 - $75 a day, so you need to do the math.
we are going to Maui again next month, and I am bringing my bike, and my wife is renting hers there. mine flies free, and her rental is about $300 total. the rental car is going to be about $3-400 more than a compact rental.