• Frugal petrol and diesel engines
• Servicing costs can be steep
• BMW has a strong reliability record

What are the running costs?

The BMW 3 Series is a surprisingly economical car, whichever engine you go for. Of those currently available, the 320i can achieve 43.5mpg according to the official WLTP figures, while the M340i can do 36.2mpg. CO2 emissions are relatively low, as well, taking the sting out of the first-year VED bill. Note that the size of the car’s wheels affects economy and emissions.

As for older 3 Series models, there are simply too many of them to give you more than a big picture of how efficient they are here. For the full details on any version you’re interested in, search for it on our specs pages.

So, what does the big picture look like? The four-cylinder petrol engines in the 318i and other versions of the 320i can easily return over 40mpg, even 50mpg if you drive gently. In the 330i, you’re looking at more like 35-40mpg. In the four-cylinder diesels, you should be able to reach at least 50mpg, while the six-cylinder diesels can get into the mid-40s. All these numbers are very competitive against equivalent models of Audi A4, Mercedes C-Class and Volvo S60.

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Servicing and warranty

BMW servicing charges can be pretty steep, but then it is a premium brand. However, you can spread the cost by taking one of its fixed-price, multi-year service plans. Regular maintenance is included, plus some potential unexpected costs. Interestingly, service intervals are based on condition, rather than mileage. On-board computers monitor the car’s health and calculate when a service is due.

BMW provides a three-year warranty with no mileage cap. That’s more generous than the industry-standard three years or 60,000 miles, but way off 10 years of coverage available on a Lexus. Even a used Kia Stinger may have more than three years of its seven-year warranty left.

Reliability

• BMW reliability is well established
• Most reliable car in 2021 FN50 survey
• There have been some safety recalls

The 3 Series has a very good reputation for reliability. It was rated the most reliable car in the 2022 Fleet News FN50 survey, which is based on real-world usage among some of the largest fleets in the UK and that’s backed up by the experiences described in our owner reviews.

Even so, we’ve found some of the 3 Series’ latest tech to be a glitchy, for instance phone connections dropping out at random. Hopefully OTA software updates have solved those issues by now.

A number of recalls affecting cars built before 2022 highlight some manufacturing defects, but the necessary rectification work should have been carried at this point. You can find full details on the government’s vehicle recall check website. If you’re buying a used 3 Series, check the service history and/or contact a dealer to find out if any recall work has been completed. Outstanding recalls are also listed on a car’s MOT certificate.