Individual cars, and car pooling, are best with small groups. When there is no more than eight people, and they all wish to do different things, there still may not be enough time for everyone to do everything. In this case, it will be best to take multiple vehicles so that people can do the things they are most interested in.
15 passenger van rental, on the other hand, is more inexpensive than any other option when a group exceeds nine individuals. It allows more people to be transported in one vehicle, which cuts down on gas expenditure, as well as the number of insurance policies needed. There are other benefits as well: such vans have more room for whatever people feel it is necessary to bring along, be it a medicine chest or even a full sized dog traveling carrier.
Chartering busses gives allows for travelling the greatest number of people. It is, however, an inefficient option unless there are at least twenty people involved - preferably more. Busses require special training in order to operate them safely. This is why chartering one usually involves securing a driver as well.
The main thing to be sure of, when arranging a trip, is to know how many people are going. This will affect not only the number of things planned, but also the kind of vehicle used. Stuffing a dozen people into a sedan would be miserable for all involved. Expecting five people to go around in their own bus would be equally ridiculous.
Source: EzineArticles.com