BMW F20/F21 (2011–2019) — History, Engines, Weak Points, Fuel Consumption

The BMW F20/F21 is the second generation of the 1 Series and, importantly for enthusiasts, the last BMW compact hatchback built on a rear-wheel-drive platform before the switch to the front-wheel-drive UKL architecture in the following model. Produced from 2011 to 2019: the five-door F20 and three-door F21.

History

The F20 replaced the E87 in 2011 (five-door body), with the three-door F21 following in 2012. The model kept the predecessor's rear-wheel-drive layout with a longitudinally mounted engine — a rarity in the compact class, where by then nearly every rival had already switched to front-wheel drive.

In 2012, the lineup gained the M135i with the turbocharged N55 inline-six (320 hp) — widely regarded as one of the best "budget M" cars the brand has ever built: a rear-wheel-drive hatchback with an engine borrowed from a proper M car. A 2015 facelift (LCI) updated the headlights, bumpers, and — more importantly — the engine lineup, with the four-cylinder N13/N20 giving way to the B37/B38/B47/B48 family, and the M135i replaced by the M140i with the new B58 turbo engine.

Production ended in 2019 with the arrival of the F40, already on the front-wheel-drive platform. For many enthusiasts, the F20/F21 remains the last "real" compact BMW in terms of historical drivetrain layout.

Engines

Petrol (pre-2015 facelift):

• N13 — 1.6 L turbo in the 116i/118i, co-developed with PSA.
• N20 — 2.0 L turbo in the 120i/125i, powerful and efficient, though not without its own weak points (see below).

Petrol (post-facelift):

• B38 / B48 — new family of 3- and 4-cylinder turbo engines in the 116i/118i/120i, cleaner and more efficient than the N13/N20.

Diesel:

• N47 (pre-2015) — 2.0 L turbodiesel in the 116d/118d/120d, plus an inline-six in the 125d.
• B37 / B47 (post-2015) — replaced the N47, fixing its predecessor's headline flaw: the timing chain's location.

M135i / M140i:

• N55 — turbocharged 3.0 L inline-six, 320 hp, in the M135i (2012–2016).
• B58 — new turbocharged 3.0 L inline-six, 340 hp, in the M140i (2017–2019) — noticeably livelier and torquier than its predecessor.

Weak Points

• N47 timing chain. The generation's headline and most notorious issue: on the diesel N47, the timing chain sits at the flywheel end, deep inside the engine — if it stretches or fails, the powertrain has to come out, making this one of the most expensive repairs in the segment. When buying a pre-2015 diesel, always ask for the chain-replacement history.
• N20 chain guides and tensioner. Wear ahead of their intended service life, showing up as rattling on cold start.
• N20 high-pressure fuel pump — a known failure point that causes power loss and engine fault codes.
• Electric water pump — on N20/N55/B-series engines, the electrically driven plastic-bodied pump is less durable than the classic mechanical unit of earlier generations.
• EGR cooler on diesels (N47/B47) — cracks over time, allowing coolant to enter the lubrication or intake system.
• Clutch on manual, rear-wheel-drive versions wears faster under spirited driving — most relevant on the M135i/M140i.

Fuel Consumption

Average combined-cycle figures — expect higher real-world numbers, especially on the turbo engines under spirited driving:

Engine	Model	Consumption, L/100km
N13/B38	116i	~6–7
N20/B48	120i	~7–8
N47/B47 (diesel)	116d / 118d	~4.5–5.5
N55	M135i	~8–9
B58	M140i	~7–8

Owner Feedback

Recurring themes from reviews and enthusiast forums, without quoting specific owners:

The M135i and M140i are near-unanimously named among the best rear-wheel-drive hot hatches of their era — the combination of a turbocharged inline-six, compact dimensions, and rear-wheel drive is virtually absent from rivals on today's used market. On diesels, owners consistently advise checking timing chain service history on pre-2015 N47-powered cars — it's the most common question when buying an older example. The petrol N20 is praised for its torque, but owners note the need to keep an eye on the water pump and high-pressure fuel pump. Overall, the range is described as one of the last "driver's" compact BMWs — after the F40 moved to the UKL platform, many enthusiasts point to the F20/F21 as the line after which the 1 Series stopped being rear-wheel drive.

Photos