2021 BMW 3 Series prices under £20,000

There are 314 used 2021 BMW 3 Series cars for sale under £20,000 from UK dealers on AskCar, as of 8 November 2026. Typical asking price £17,500 (the median: half cost less, half cost more). The cheapest is £10,000. The middle half are priced between £15,500 and £19,000. Median mileage: about 71,000 miles.

Dealers lowered the asking price on more than a third of 2021 BMW 3 Series cars under £20,000: 125 of the 314 in the 14 days to 8 November 2026.

AskCar lists 7,130 used BMW 3 Series across the UK, from 2,708 dealerships.

As of 8 November 2026, AskCar lists 595,629 cars and vans from 12,891 UK dealerships, read daily from dealer websites: over 99% of UK dealer used car adverts. No dealer pays to be listed.

2021 BMW 3 Series cars for sale now under £20,000, page 1 of 7

This page picks out up to 10 cars in each of these groups: best value, cheapest, lowest mileage, recently reduced and newly advertised. A car in more than one group is listed in full once. The groups pick only from cars with photos and an AskCar estimate, priced at £500 or more and no more than 25% under that estimate. 291 of the 300 cars listed here meet these rules. Pages 2 to 7 list every other 2021 BMW 3 Series car, cheapest first, including the 9 the groups do not pick from.

The AskCar estimate is our expected asking price for that one car, from its model, age, mileage and specification, using the 6,822 priced BMW 3 Series adverts on AskCar as of 8 November 2026. The figures on this page describe the cars advertised, not a valuation of every 2021 BMW 3 Series.

Each car: year, make, model, engine and trim, power, gearbox, fuel, body, doors, colour; mileage; price and its changes; how the price compares with the AskCar estimate; emissions standard and ULEZ compliance where it holds; MOT; dealer and town; AskCar page. Each car's AskCar page has its full price history and cheaper cars like it.

This list leaves out 14 cars whose advertised mileage is lower than the mileage recorded at their last MOT test.

Best value 2021 BMW 3 Series: priced furthest below the AskCar estimate

These 10 are priced 12% to 23% under their AskCar estimate. Their asking prices run from £11,995 to £19,995.

Cheapest 2021 BMW 3 Series: the lowest asking prices

These 10 are priced £10,000 to £11,995. They have covered 82,791 to 137,812 miles.

Lowest-mileage 2021 BMW 3 Series

These 10 have covered 24,802 to 35,998 miles. Their asking prices run from £15,895 to £19,999.

Recently reduced 2021 BMW 3 Series: the biggest price reductions in the 14 days to 8 November 2026

The dealer lowered the asking price on each of these 10 in the 14 days to 8 November 2026. Their reductions since AskCar first saw them run from £2,099 to £4,000.

Newly advertised 2021 BMW 3 Series: first seen by AskCar in the 7 days to 8 November 2026

These 10 are the most recently advertised. Cars first seen on the same day are listed cheapest first.

BMW 3 Series by gearbox, fuel and body

BMW 3 Series under £20,000 by gearbox, fuel and body

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