Liverpool has the lowest prices at 2.3% below the national average, according to analysis of more than 200,000 UK listings by car classified ad website CarGurus.
The research shows that cities located in close proximity to other major conurbations, such as Manchester, Nottingham, Sheffield and Birmingham, generally have lower prices than more isolated cities, including Plymouth, Norwich and Bristol.
Analysts believe a higher concentration of competing dealerships drives prices down.
Plymouth was ranked as the most expensive city for used cars in the UK, with sellers typically asking for 5% above the national average.
The market price of a 2013 Volkswagen Golf is £11,777 in Plymouth, compared with just £10,755 in Liverpool, the study found.
CarGurus spokeswoman Sarah Welch said: "Our data shows that prices for comparable used cars do vary quite a bit across the nation.
"Although not all consumers will be willing to travel afar for a deal, this research shows that motorists can sometimes benefit from expanding their search radius when shopping for a bargain. For consumers not keen to travel so far, some dealers will offer delivery services, so it is worth asking."
The report found that the average price of a used car in the UK is £12,074.
- Here are the 10 most affordable cities in the UK to buy a used car, according to CarGurus. Percentage below the national average for prices is in brackets:
1. Liverpool (2.3%)
2. Leeds (2.2%)
3. Bradford (2.1%)
4. Manchester (2.1%)
5. Sheffield (2%)
6. Stoke (2%)
7. Nottingham (1.7%)
8. Leicester (0.9%)
9. Birmingham (0.8%)
10. Glasgow (0.5%)