Gas prices are well below record highs from a few years ago, but that doesn’t mean you’re not paying more than you should to fill up your car every week.

In fact, a GasBuddy study found that Americans are more likely to overpay when prices are lower.

Read more: Best and worst auto insurance companies

Where you’re most likely to pay too much for gas

There is a greater variance or “spread” in gas prices during low-price cycles, GasBuddy’s analysts discovered. The price of gas can also vary dramatically within a city — even from street corner to corner.

These 10 cities have the widest price spread, the difference between the highest and lowest gas stations:

1. Washington, DC: $1.22
2. Los Angeles, CA: $1.12
3. San Francisco, CA: $1.12
4. San Diego, CA: $1.02
5. Seattle, WA: $0.84
6. Chicago, IL: $0.82
7. Portland, OR: $0.76
8. New York, NY: $0.75
9. Boston, MA: $0.62
10. Philadelphia, PA: $0.61

“Spreads can vary based on factors like local competition and geographic location,” said Patrick DeHaan, senior petroleum analyst for GasBuddy. “We noticed some commonalities amongst the cities ranked the highest: they tend to be sprawling with a major connecting highway running through them. Additionally, they have the presence of a large warehouse retailer in the market. The good news for drivers in these areas is that there are opportunities to save money if you know where to look and choose to shop wisely.”

If you’re looking to save money on gas, you may want to fill up on a different day of the week!

After analyzing three years of fuel price data, GasBuddy found that Monday offers the lowest average price, making it the best day of the week to buy gas.

Thursday, on the other hand, is the worst day of the week to buy gas.

Buying gas from a station on this list is better for your car