The regional variation of used-car prices

How much does a Honda Accord cost? The answer might depend on where you live.

The price of a used car can swing more than 20 percentage points depending on what metro area you're shopping in, according to a study from an online used-car marketplace. The findings show trends in regional economics and potential opportunities for well-planned "carbitrage."

That 2013 Accord you were shopping for costs an average of $15,918 in Miami, the nation's cheapest place to buy a used car, according to the data. In Fresno California, the equivalent car would cost $18,297.

That's according to data from CarGurus.com, provided exclusively to CNBC. CarGurus, a Massachusetts-based online marketplace for used cars, crunched the numbers on more than five million used cars listed for sale in the 98 largest metro areas in the country.

The study found that relative to the national average, Miami had the cheapest price for used cars, followed by Cleveland and Akron, Ohio. Many of the least affordable metro areas were in the West: Fresno, Albuquerque, New Mexico and Reno, Nevada are at the bottom of the list.

Buying a used car is often a maze of known unknowns with price being one of the biggest factors. Car buyers looking for a 2007 Chevy Tahoe with 130,800 miles in Wichita, Kansas could save an average of $1,200 by driving 160 miles south to Oklahoma City, Oklahoma for example.

"While staying local makes sense for most car shoppers, they also may not be aware that car prices do vary across the country," said Lisa Rosenberg, a data analyst at CarGurus. "Expanding a car search to a nearby city can sometimes yield significant savings, and for those truly driven by price, it might be worth it."

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So what's going on here? For one thing, the variation shows regional patterns: Used cars in the Northeast are generally priced below the national average while those in the South and West are above.

According to CarGurus' data, there's a weak inverse correlation between car prices and population density. That means buyers sometimes can find better deals in more spread-out cities, which makes sense because the denser the population, the more transportation options there are likely to be.

There's a similarly weak inverse correlation between price and total number of listings in a metro area. CarGurus didn't find any correlation with a number of other variables, from number of dealerships in a metro area to the median one-bedroom rent for an area.

The price of used cars is generally more volatile and subject to economic conditions than that of new cars. During the most recent recession for example, the relative price of used cars fell around 10 percent, according to consumer price index figures from the Bureau of Labor Statistics.