Roughly 418 miles to drive, calculations assume gas tank starts empty and is filled to exactly 418 miles, and prices are converted from per gallon to per mile, using personal car's 28 MPG.
Filling 418 miles in Lexington at average price of $0.094 per mile costs $39.292. Filling 418 miles in St. Charles at average price of $0.162 per mile costs $67.716. This means leaving from and filling gas in Lexington is cheaper than in St. Charles by $28.42.