Really? What sort of math do you use to predict the cost of fuel throughout the life of the car? Crystal ball or magic 8 ball?
FYI, I think a heated steering wheel is maybe the dumbest feature of all time. Any time it's cold enough to need one, I'm wearing my gloves anyway. If you leave the house in cold conditions without gloves, you're being foolish.
Some of us prefer driving without gloves. I didn't put mine on until after parking, despite it being -4°F on the drive to work this morning.
You don't need to predict the cost to predict which combination saves more gas (as opposed to saving more on gas). You just need to assume the same miles pa and calculate gallons / year based on EPA mpg or some other consistent data source if it better matches your usage. Results will depend on the exact models compared looks to me as though the getting the hybrid in the Highlander saves the most, then the Prius over the Corolla, with the RAV 4 hybrid saving the least as its fuel consumption doesn't seem to be that much less than a normal RAV 4. PS: its easier if you work in L / 100km. Then you just have to look at the difference between ratings.
I used gallons per year which avoids dollars and life of car issues. If, like me miles driven each year is a constant, you can compare across vehicles. I drive 30,000 miles a year since 2002.