Actually, though, I think since your kids are in carseats rather than boosters, that you will do better. The reason is that once they are installed, you don't have to try to reach buckles between seats. The kids will use the harnesses.
A friend has a Sedona and loves it--they bought it for the price and while it doesn't have the niceties of some of the other cars, it fits all her kids and a friend safely!
Oh, and if you do the math, you can find out how much more you will spend in gas for the year. I was SHOCKED at how small of a difference it was for me.