There is a down side to the lower gas/diesel prices.
Over 250,000 layoffs in the oil and gas industry thus far in 2015, with predictions that the total number will be 500,000 total layoffs within the next 6 months.
http://www.theoilandgasyear.com/news...since-january/
Each of those US jobs result in a net reduction in tax revenue of about $20k (including the taxes that their employer was paying).
http://www.usdebtclock.org/
Someone (the remaining employed, who are not in the 160,000,000 US citizens getting government assistance) will have to catch up their slack and:
1) Pay the taxes lost by these now unemployed (and the tax revenue not paid by their former employers).
2) Pay unemployment benefits to those who lost their jobs.
There is no free lunch.