WASHINGTON (MarketWatch) — The OPEC oil cartel is not happy about falling gasoline prices, but Americans are pretty chipper about it. Consumers confidence soared in October to the highest level in seven years in no small part because Americans are paying less to fill up at the gas station.

How much less? Regular gasoline has fallen to a nationwide average of $3.06 a gallon from as high as $3.70 in late June. The 17% plunge in gasoline over the past four months put prices at a four-year low and they are likely to go even lower. Many analysts think gasoline could fall below $3 a gallon — in many places the price already has ) and stay there until at least early next year.

The savings are significant and come as welcome relief to consumers whose weekly paychecks are still barely growing five years after the end of the Great Recession.

Also see: Consumer stocks should eventually benefit from low gas prices

Consider a family that buys 90 gallons a month to fill up two cars. Household savings would total about $60 a month at current prices compared to what a family would have paid early in the summer. That’s $720 over a full year.

Here’s another way to look at it. The average individual spent as much as 4% of his annual income on gasoline in mid-2008 during the last big global spike in oil prices. Now the percentage each person spends is about to fall below 3% for the first time since 2010. Sounds small but that represents big savings.

Declining prices are an unabashedly good thing for the broader economy, even if they make America’s new “fracking” oil barons shudder in places such as North Dakota, Colorado and Pennsylvania. Lower energy prices cut shipping and other costs for companies ranging from e-tailers such as Amazon AMZN, -1.46% to passenger airlines like Southwest LUV, -5.47% .

Many economists also predict Americans will use their savings at the pump to buy other goods and services — and pump up the U.S. economy in the process.

“We expect the surge in consumer confidence to assist in holiday retail sales growth this year,” said Chris G. Christopher Jr. director of U.S. consumer economics at IHS Global Insight. “Elevated levels of consumer confidence assist shoppers spending on discretionary items, especially in November and December.”

What could end the party? Saudi Arabia or other big international oil suppliers could slash production to boost prices. Or resurgent American oil producers could find it uneconomical to extract much more oil from the ground unless prices stabilize. A barrel of oil CLZ24, +0.04% has slumped to around $82 from nearly $104 early in the summer.

Yet almost no one in the industry expects that to happen before the end of the year — if at all — unless prices fall dramatically lower.