Americans are pumping fewer dollars into their gas tanks and ending up with more money. Image source: Mike Mozart, Flickr.

Something interesting has been happening in America: Though many households have not noticed it, they've been receiving a bit of a financial windfall. American households have been enjoying an average of about $700 extra dollars, thanks to the falling price of oil. Most folks have not put that money to good use, though. Don't be one of those people.

The average price of gas in America spent a lot of time well above $3.50 per gallon last year, and it plunged to $2.31 recently. Given average American consumption levels, it has been estimated that the typical American will save about $700 in 2015 thanks to a lower price for gas. That's quite a chunk of change, and it could make a difference to many people, but a recent JPMorgan Chase report, based on a study of millions of debit and credit card accounts, finds that people have already spent about 80% of that money, and mainly not in ways that boost their financial condition.

Some 20% of the savings went to restaurants, with department stores, entertainment, electronics, and appliances also benefiting. A Gallup Poll on the topic differs in its findings, with only 25% of survey respondents saying they were spending the money, and most people claiming to be saving it or paying bills. The truth may be somewhere in the middle, as survey respondents may paint a rosier picture of themselves, and the JPMorgan Chase report may have a bias due to being based on those with credit or debit accounts with the company.

Still, the bottom line is that most of us are in a position to realize significant savings from lower gas prices, but too many people are not making the most of it.

Let's look at several ways to use that windfall more productively.

Lower gas prices are leaving you with more money in your pocket. Image source: Pixabay.

Address debt
One smart thing to do with your gas savings is to pay down debt -- especially high-interest rate debt such as that associated with credit cards. According to data from the Federal Reserve, among households with debt, the average credit card debt load was $16,140 -- on top of an average mortgage debt of $155,361 and average student loan debt of $31,946. If you could lop $700 off of your debt, on which you were being charged, say, 25% in annual interest, you would avoid paying $175 in interest charges -- each year.

Grow your wealth
If you're not saddled with debt, consider growing your wealth with that $700. If you invest it in the stock market and earn an annual average of 10% over 25 years, it will grow to more than $7,500. If gas prices stay low for another year, and you save another $700, in 24 years, it will grow to about $6,900, for a two-year total of $14,400. That kind of money can make a difference in your retirement. It's almost as much as the average annual Social Security retirement benefit!

These prices, from June, are well above current average prices. Image source: Mike Mozart, Flickr.

How to collect the windfall
You never actually see the $700 in savings, which is why it's so easy to just spend. In order to avoid that and put it to better use, if you can swing it, just deposit $700 into your saving or investment account, or send a check for that toward your credit card debt. If you can't do that, take $60 out of your pocket each month and apply it toward your debt or savings.

Note, too, that your household's windfall might be smaller than $700, if you use less gas than usual – or it might be far larger. It's based on an estimate of about $1,800  for the average household's spending on gas in 2015, vs. $2,500 in 2014. Whip out your calculator and estimate how much you spend on gas each year to see what your savings might be. If you heat your home with oil, you will likely enjoy a double windfall.

Don't let 2015 go by without taking note of any big savings that have come your way. Aim to capture such windfalls and put them to productive use, as they can improve your financial condition.

Longtime Fool specialist Selena Maranjian, whom you can follow on Twitter, owns shares of JPMorgan Chase. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.