Where I live it has been many years since the fuel we out in our cars was only $5 a gallon.. I think it is approaching the $10 mark these days. I live in the country and have to travel more than 20 miles every day to get to work. If, like me, you are spending 1/4 of your income just in fuel to get to work you will porbably have more of an incentive.
In this country, the United Kingdom, a red dyed agricultral diesel is available illegialls for only a couple of dollars per gallon. Its as good as regular diesel but if you get caught using this tax free fuel on the roads you face a big fine but if you drive a lot of miles its worth doing.