Gas prices near record lows. Which US city has the cheapest?

Gas prices are the lowest they've been in four years. The highest US gas prices are in San Francisco, while commuters in one Southern city are paying just $2.73 a gallon. 

If you're reading this while preparing for you morning commute, take solace in the fact that it's likely costing you a little less to drive to work than it did at this time last year.

Gasoline prices are as low as they've been in four years, although not quite matching the low prices seen in 2010, according to the latest Lundberg survey (via CNBC) of fuel prices.

As of October 24, the average price of gasoline was down 18 cents to $3.08 a gallon.

Researchers say that's the lowest prices have been since December 2010, and it's all thanks to a steep drop in crude-oil prices.

There have been ample supplies and weak demand for crude oil over the past four months, driving prices down.

Of course, what you'll actually pay depends somewhat on where in the country you live.

The survey found that San Francisco had the highest gas prices, with an average of $3.45 per gallon, while Memphis had the lowest, with drivers there paying an average of $2,73 per gallon.

Prices are down 29 cents compared to the same time a year ago, and have continued to decline since May, when they hit a year-high $3.72 per gallon.

The current price drop follows steep declines witnessed around Labor Day, also linked to a drop in crude-oil prices ahead of Autumn, typically a period of reduced oil buying.

Lower gas prices are good news for consumers, but not necessarily for makers of fuel-efficient cars.

While gas prices are low, sales of green cars tend to drop as well. because saving fuel becomes less of an economic benefit for buyers.

That's because, in the end, many potential green-car buyers are more concerned about a different kind of green: cash.