How to split the cost? I would lean towards 1/3, or if you had to increase the car rental size because of the extra adult and that was more than 1/3 the cost, then that amount.
I just wanted to mention some other items. Insurance for the rental car?
Are you getting it, or passing on it.
Some of it depends on what type of car insurance you have at home and if it covers you in the event of an accident in a rented car?
Reason i ask is because, when i travel, i always decline the rental car insurance. I traveled with a friend in college and was shocked to learn at the end of the trip, she included the car insurance. She was the main driver, and in retrospect she wanted the insurance because she had several tickets, accidents, and had a previous accident in a rental car.
We had a plan, i'd pay for rental car, and she bought some tickets for our several days in florida (only 1 day was at disney).
Well, costs of a rental car when purchasing the insurance $/day is a lot higher than the regular rate. I still paid my friend the entire amount for the rental car, however its something to discuss if your splitting expenses.
I guess if your not sure how to split the cost of the rental 50/50, are you going to talk about declining or accepting the insurance too.
Plus, some people prefer to prepay the gas, and not be bothered with refilling the gas talk. Its a set $$ amount. However, if you aren't emptying the tank, you loosing out on some $$. Its a time spent on vacation value (wanting every precious second in the parks), or filling up the tank time to save money.
So, the gas question comes into play too. Are you going to make the single adult contribute what amount the cost of gas?
50/50 25/75 ?
Good luck in your decision. You might want to go thru some of your other expenses you might be splitting, and discuss money issues before the trip. So everyone is on the same page.
Your looking at the situation in a my family and his family. However his family only consists of 1 person and yours consists of 3. So, if your doing strictly numbers game his cost is 1/4.
Also if your splitting checks for meals, or if you do the dining package. I'd be careful if your just asking to split the check in 1/4, or actually do the math. If he's a big eater, and your family eats like birds, you'll end up with some of his bill. If he is a light eater and only gets an entrea and your family are big eaters, desserts, appetizers, entreas at restraunts then he's getting stuck with a bigger bill than he's actually consuming.
If your worried about car rental, i'd be discussing all the costs associated with the trip up front to avoid causing surprise $$ expenses on either side.
Connie