Mark:
It is all about weight; not numbers. How much do the 4 adults weigh? What is the length of your average trip which determines how much fuel you need. The SR22 is a great full fuel 3 person airplane. But if the people are heavy and you need to go far, full fuel and 4 people will not make the weight limit.
The G#3, G5 and G6 airplanes can carry 92 gallons of gas. At the typical fuel burns that can carry you pretty far in distance. The empty weights are in the 2400 pound range and the maximum gross weight of a G5/G6 is 3600 pounds. For a G1,G2 or G3 MGW is 3400. Just do the math and your will get your own answer using 6 pounds/gallon for fuel weight.