2021 BMW 4 Series 2.0 420i M Sport

Overview

• Make: BMW
• Model: 4 Series
• Trim: M Sport
• Version: 2.0 420i M Sport Auto RWD Euro 6 (s/s) 2dr (181 bhp)
• Year: 2021
• Mileage: 37,652 miles
• Fuel: Petrol
• Body: Convertible, 2 doors, 4 seats
• Engine: 2.0 litres, 181 bhp
• Gearbox: Automatic
• Drive: Rear-wheel drive
• Colour: White
• CO2: 160 g/km
• Emissions standard: Euro 6, ULEZ compliant

About this car

This 2021 BMW 4 Series M Sport is advertised with 37,652 miles, approximately 6,500 below the typical mileage for its age. The AskCar estimate for this car is £24,624. It is priced at £22,550, which is £2,074 below that estimate. To work out the AskCar estimate, we analyse UK dealer adverts for 1,814 BMW 4 Series cars across different ages and specifications. The asking price is now £3,550 lower than when we first recorded the advert 129 days ago. Its advertised mileage matches the government's MOT record. It is for sale at Car Planet Watford in Rickmansworth. How to contact the dealer and its opening hours are on this AskCar page.

Stock data as of 4 November 2026.

How we estimate prices and check cars

Price

Good value: £2,074 (8%) under the AskCar estimate of £24,624.

The AskCar estimate is our expected asking price for this car. It uses UK dealer asking prices, accounting for make, model, trim, version, age, mileage, fuel, gearbox, body type, driven wheels, engine size and power. It is an advertised price, not a confirmed sale price.

It draws on 1,814 priced BMW 4 Series adverts across different ages and specifications, as of 4 November 2026.

A 2021 BMW 4 Series with the 2.0 petrol engine is typically advertised at £24,000: the median of the 144 for sale on AskCar, as of 4 November 2026.

Time on sale

This 2021 BMW 4 Series has been on sale for at least 129 days.

Price history

AskCar first saw this advert on 28 June 2026 at £26,100. Its asking price is now £22,550, £3,550 less. The latest price cut was seen on 30 October 2026.

Price changes recorded:

• 28 June 2026: £26,100
• 13 July 2026: £26,300
• 20 July 2026: £26,200
• 27 July 2026: £25,900
• 3 August 2026: £25,600
• 10 August 2026: £25,350
• 18 August 2026: £25,050
• 25 August 2026: £25,000
• 1 September 2026: £24,950
• 8 September 2026: £24,850
• 17 September 2026: £24,650
• 23 September 2026: £24,350
• 28 September 2026: £24,050
• 5 October 2026: £23,750
• 11 October 2026: £23,450
• 17 October 2026: £23,150
• 23 October 2026: £22,850
• 30 October 2026: £22,550

Mileage and MOT

MOT, from the government's MOT records (DVSA, the Driver and Vehicle Standards Agency), as of 4 November 2026: valid until 30 June 2027.

It has had 3 MOTs. The latest, on 1 July 2026, passed.

There were no advisories at the latest test.

Mileage at that test: 37,673 miles, which matches the advertised 37,652 miles.

Advertised mileage is about 6,500 miles lower than the median mileage of a 2021 BMW 4 Series on AskCar.

Similar cars

26 other 2021 BMW 4 Series M Sport 2.0 petrol automatic convertibles are for sale at UK dealers, from £18,990 to £33,950, as of 4 November 2026.

The 3 closest to this car in mileage:

• 2021 BMW 4 Series M Sport, 2.0 petrol convertible, blue. Mileage: 36,940 miles. Price: £25,489, £2,939 more than this car. Dealer: MNM Cars in Preston. AskCar page: https://askcar.co.uk/car/bmw-4-series-2021-d43d415dbd4e
• 2021 BMW 4 Series M Sport, 2.0 petrol convertible, blue. Mileage: 36,115 miles. Price: £26,750, £4,200 more than this car. Dealer: Sytner Luton BMW in Luton. AskCar page: https://askcar.co.uk/car/bmw-4-series-2021-4689bf59ccf8
• 2021 BMW 4 Series M Sport, 2.0 petrol convertible, white. Mileage: 35,008 miles. Price: £25,990, £3,440 more than this car. Dealer: Alpha Motors in Wigan. AskCar page: https://askcar.co.uk/car/bmw-4-series-2021-dfd9ebfe4c58

• The nearest: 2021 BMW 4 Series M Sport, 2.0 petrol convertible, green, 6 miles from this car. Mileage: 12,250 miles. Price: £33,950, £11,400 more than this car. Dealer: Kams Cars in Borehamwood. AskCar page: https://askcar.co.uk/car/bmw-4-series-2021-aea4aa4c4d93