What used BMW 3 Series saloon will I get for my budget?
You’ll need a budget of at least £5500 for a sixth-generation 3 Series and even then you’ll be looking at cars that are either write-offs, high-mileage or both.
A petrol model with less than 100,000 miles on the clock can be picked up for around £8000. Increasing the budget to £9000 will get you a 320d variant that’s averaged a reasonable 10,000 or so miles per year. If you’re looking at a 316i, bear in mind that two power outputs are available, with little price difference to separate them.
The ActiveHybrid model tends to be a rarity on the used market and is too niche to recommend; the more recent plug-in 330e version makes more sense, but you'll need around £15,000 to buy one with an average mileage.
Meanwhile, if you want a used 3 Series with a six-cylinder engine – and we can understand why you might – expect to pay a minimum of around £12,000 for one with an average mileage.
How much does it cost to run a BMW 3 Series saloon?
There’s a reason most buyers opt for the 2.0 diesel 320d, and that’s because it offers good performance while also being cheap to run. In post-2015 facelift 320d Efficient Dynamics form, the official fuel economy figure is 74.3mpg, which isn’t at all bad from a car that can also get from 0-62mph in just over seven seconds. What’s more, the 99g/km CO2 output also makes it exempt from road tax.
If you’re looking at a pre-facelift 3 Series, it’s still possible to pick up a 1.6 or 2.0 diesel that won’t cost any more than £20 or £30 per year to tax and will average more than 50mpg in normal driving.
Petrol engines cost from £120 per year to tax and will generally struggle to crack 35mpg in regular driving. Opt for a six-cylinder petrol engine and you’ll enjoy stunning performance at a cost of about 30mpg in average fuel economy and an annual tax bill of at least £195.
The plug-in hybrid 330e has an on-paper claimed average fuel consumption of a startling 148.7mpg, with corresponding CO2 emissions of just 49g/km. As is the case with most hybrids, you're unlikely to see anywhere near this figure in the real world, unless your journeys are short and you have access to a charging point at either end.
It’s worth remembering that if you buy a 3 Series registered after 1 April 2017, it will cost you £140 per year to tax regardless of which engine you go for, because of changes in the road tax system. Just make sure its on-the-road price doesn't exceed £40,000, otherwise it'll attract a supplementary luxury car tax, currently £310 a year.
BMW offers its new cars with a five-year fixed-price servicing package, so it’s worth seeing if the 3 Series you are looking at is still covered under this. Even if it’s not, servicing costs aren’t prohibitive; you’ll pay from about £250 at a BMW main dealer when an inspection is due roughly every two years or 15,000 miles (the car will tell you exactly when).