Horsepower with mileage options

I did a quick calculation. At my gas price up here in Canada which is ridiculous. If i put 5000 miles a season at 14 mpg would cost me about $1600.00 now if I increased my fuel mileage by 25% which is pretty optimistic it would be at 17.5 mpg now costing about $1250.00, saving $350 a year. If you spent a $1000 it would take 3 years to break even but the things we're talking about could easily cost $3000-6000 and 9-18 years to pay back.