Used car guide · 2004–2005

BMW 645i common problems and MOT failures

What goes wrong on a used BMW 645i, year by year: known faults from UK buying guides, the parts flagged at MOT more than on other cars (from 4,710 MOTs done during 2023–2025), and what to check before you buy one.

4,710MOTs done in 2023–2025, all years of this model

Pick the year

Most years have their own guide. The year is when the car was first registered (it’s on the logbook, or check the reg below).

20052004

What usually goes wrong with a BMW 645i?

We haven’t found widely reported faults for the BMW 645i in the UK buying guides we use yet. That doesn’t mean it has none, so check the car carefully and look at the MOT weak spots below.

Common BMW 645i MOT failures to check

Parts flagged at MOT well above the usual rate for cars the same age. From the DVSA’s results for every MOT done in Great Britain during 2023–2025.

  • Engine oil leaks

    up to 2.2× usual

    Stands out on cars registered in 2004 and 2005.

    Rough price £80–£600 our estimate

    At the viewing: Look under the engine and where the car is usually parked for fresh oil. Ask whether the leak has been looked at.

  • Suspension arm bushes and joints

    up to 1.7× usual

    Stands out on cars registered in 2004 and 2005.

    Rough price £120–£180 (one arm) ClickMechanic

    At the viewing: Listen for clunks over bumps and feel for the steering wandering. Worn arm bushes show as cracked rubber near the wheels.

BMW 645i MOT pass rate by year

Older cars fail more, so compare each year with all cars registered the same year.

YearPass first timeAll cars that yearMOT tests
200571%57% +141,459
200471%57% +143,251

Questions to ask the seller before buying a BMW 645i

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

  1. Any recent work on the engine oil leaks? (Flagged at MOT 2.2× as often on the BMW 645i as on other cars the same age.)
  2. Any recent work on the suspension arm bushes and joints? (Flagged at MOT 1.7× as often on the BMW 645i as on other cars the same age.)
  3. Can I see the service history and receipts for any big jobs?

Looking at a BMW 645i?

Check the actual car: its own MOT history, whether it already shows these weak spots and what to ask the seller. Free, no sign-up.

Where this comes from: MOT figures are the DVSA’s anonymised results for every MOT test done in Great Britain during 2023–2025, grouped by the year each car was first registered. How many are on the road is from the Department for Transport’s vehicle licensing statistics. Known faults are from UK buying guides, in our own words, with links. How we score