Multiple IF Statements w/ Changing Conditions - Need Help!

Hello,

So I'm trying to build a buy/lease analysis model for cars, and in that model I am including the estimated cost of gasoline,

I have two tabs, one with the inputs on average price of gasoline for several states (diesel and regular) and the other tab with the formulas for calculating the cost,

My trouble is building an equation that will display the cost of gasoline in a cell based on two conditions that may change from a drop-down list.

I assume this would be a VLOOKUP, but I am unsure.

Any help would be greatly appreciated.

I've attached an example spreadsheet that may better explain my problem.

Thanks!

File should be attached.