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BMW M135i (F20) | PH Used Buying Guide

BMW no longer builds a straight-six, rear-drive hatchback. Here's how to buy back the good times...

By Tony Middlehurst / Tuesday, January 28, 2020

Big car, little engine. Little car, big engine. Given such a choice, anyone with a spirit of adventure would surely go for option two. And anyone needing to combine that 'lust for thrust' spirit with a requirement for a little practicality would surely be looking quite hard at the BMW M135i.

Bursting forth from a cloud of shock, awe and wonderment at the 2012 Geneva car show in F21 three-door format, a few months after the launch of the F20 five-door 1 Series at Frankfurt, the M135i was the first offering from the new M Performance sub-brand. It immediately went to the top of many punters' lease car hitlists in the summer of 2012.

Once the initial hysteria had been replaced by the cold light of day, a few flaws took some of the shine off, but the first 1500kg M135i was - and still is - a highly desirable pocket rocket with 320-325hp, a power to weight ratio of over 210hp per tonne, and a 0-62mph time in the very low fives, or high fours in the auto. All that with four (or at a pinch five) seats and a combined average fuel consumption of 35mpg. No wonder it was so sought after.

A commonly-used community word for these M Performance 135is and 140is is 'M-Lites' because their running gear spec isn't quite up to that of the 'proper' M cars. The suspension bushes are softer, the wheel alignment geometry and steering aren't as sharp, the brakes and tyres aren't as beefy, and they don't have a limited slip diff. None of this is necessarily a bad thing as this lite spec can keep your ownership costs lite too.

Some say that the latest M135i, complete with the latest BMW 'improvements' - big grille, the impression of a large front overhang, and a generally blobbier look - is a styling step in the wrong direction, and especially so from the 2015 LCI facelift. On the driving front, diehards have bemoaned the switch from a rear-drive chassis powered by a proper big inline six to a four-wheel driver propelled by a transverse 2-litre four. They've also hated the replacement of the handbrake by an electric switch that, when activated on the move, simply brings you smoothly to a halt. Where's the fun in that? The rowdy ruffian element that so attracted people to the original car has now been polished to a smooth finish. They've even added more room in the back. The M has been sanitised.

Which is fine because the new four-pot M135i is, as is usually the way with these things, an even quicker means of getting about the place than any of its forebears. But here's another question: which of the two M135is, original or new, do you think will go on to achieve classic status? Precisely. So here we are with our PH Buyer's Guide to the original M135i.

Before we get into the detail, here's a quick timeline on model year differences. The first cars of summer 2012 had a turbo with a Pneumatic Waste Gate. A year later, the turbo got a bigger outlet and a new Electric Waste Gate, with automatic lights and wipers moving off the options list and onto the standard equipment list. A new steering wheel and new tyre pressure/temperature sensors came along in 2014, along with Bluetooth for music streaming (week 10 and on cars) and an SOS button.

A facelift in spring 2015 (the so-called Life Cycle Impulse or LCI) improved the overall look, added 5hp to match the M135i up with the M235i, boosted cargo handling via a couple of extra storage bins and a luggage net, and binned the Xenon headlights in favour of LEDs. The 'full black' instrument panel became standard equipment in summer 2015.

The 8-speed ZF auto was tweaked at this time too, accentuating the difference beyween Comfort and Sport models and speeding up shift times. There was also Predictive Shift, which worked with the now-standard sat nav to ensure that the right gear was in place for the next corner. Factory options included an MPE exhaust for under £700 and an LSD for £2,520. Today, you can get a Quaife LSD from Birds for around the same sort of money.

Bodywork & Interior

As noted earlier, the M135i was launched as a three-door but it was also available as an F20 five-door. Which one you choose now will of course depend on your needs, but don't go thinking that just because it's got five doors it will have plenty of room in the back. It won't.

In terms of durability, hard rubber seals on the 3-door cars can erode the paint on the door shut areas over time. Helicopter tape on the B-pillar will protect it. Tailgates clatter, especially in cold weather. This was a problem on the first-gen Ones that was never really resolved in the gen-twos. Again the fix is tape-based, using Tesa cloth tape to be precise.

While you're round the back, have a look for paint blistering on the boot lid. Exhaust tips are known to corrode too. Tyre pressure monitors don't usually fail but the readings they give err on the low side.

Inside, option packs like Visibility and Driver Comfort, which included cruise and rear park sensors, are never a bad thing in a used M135i as they help to bolster values. Pro Nav runs on a wide screen, while Business Nav has a smaller square screen with a shiny black surround. Cars without navigation have a matt-surround square screen. The full black panel display option is well liked, as are the Harman Kardon audio, the front and rear park sensors and the rear view camera, but the jury is out on factory-fit dimmed glass as it can look a bit chavvy to some eyes, and it's not as if you can remove it.

Not everybody gets on with the right-offset pedals, so make sure you try before you buy. The lumbar support seat option is very much worth having too. Some owners have reported rust on their seat frames, but you'd need to grovel around a bit to see it. Why not just forget about it, in that case.

Engine & Transmission

Making its debut in 2010 in the F07 5 Series Gran Turismo, the M135i's 3.0-litre N55 engine was BMW's first inline six to have a twin-scroll turbocharger (its N54 predecessor being a conventional twin-turbo unit with piezo-electric injectors). The N55 was eventually superseded by the B58, a more efficient unit which powered the M140i replacement in 2016, although the B58 did have its own issues like weak radiators and an odd rattle from the valve in the left-hand exhausts on cold startups.

The N55 went out with a small bang, with max power increasing from around 320hp to 325hp in post-2015 LCI cars. As our own Dan Prosser found with his '62-plate long-termer, a £2700 (inc VAT) Birds remap will hoist factory power to 390hp and 420lb ft, which is pretty much the practical limit for the N55 before ignition timing starts to become a problem. Even on a standard exhaust the N55 sounds great.

Problems? Not that many. Faulty cooling fan sensors on early cars caused the fans to come on even when the engine was cold. That was sorted under warranty. The engine oil and filter should be changed every 18,000 miles or 2 years - you'll need 6.5 litres of 0w30 full synth - with the air filter and spark plugs replaced at every other oil change. M135is can use up to a litre of oil ever 1000 miles, incidentally, a rate of consumption deemed to be acceptable by BMW. Bore wash caused by hard driving will accelerate that consumption. Some owners use heavier 0w40 or 5w40 grades to reduce seal leakage. There's no actual dipstick: you have to rely on the iDrive readout to measure the amount of oil in the motor and it's not massively accurate. To avoid overfilling, the advice is to wait until iDrive tells you to add a litre within the next 100 miles. Then do it.

If you use 95 fuel rather than 97, that's fine, but you may be forsaking a little power when the engine gets hot. Luckily, this engine is not a heavy drinker. With the cruise control set in the mid-70s you should get mpg figures in the mid to high thirties. In town, expect up to 10mpg less. Move it from Comfort to Sport and give it some welly and that's another 10mpg gone, but you won't really care. Overall, and even with a fair bit of right-footular enthusiasm, you'd be well within your rights to expect low 30s in the manual or mid-30s from the high-top-geared 8-speed auto - which is a brilliant transmission, by the way. Apart from its slickness in use, with launch control on late 2014-on cars plus variable change speeds as well as the usual kickdown and manual paddles, the potential extra economy of that high gearing plus a coasting mode makes it cheaper to tax. It's also more expensive to replace. A recon box fitted by BMW used to cost up to £8k. Problems that can lead to that include whining in second, fourth and/or reverse. It's worth considering a warranty of some kind to cover yourself for that.

The manual box was only chosen by one in five M135i buyers, but it's another worthy if not especially satisfying ZF component. Specifically it's the GS6-45BZ/DZ, a catchy title for a transmission with Start/Stop (which works better in the manual than it does in the auto) and another of these miracle 'lifetime oil' setups that nobody believes in. Same goes for the diff. This is quite a gnarly environment in an M135i, so again you are well advised to ignore the official advice to ignore it, and change the diff oil.

Suspension & Steering

The M135i came out in 2012, a year into the life of the F20/F21 1 Series. These second-generation cars went a long way towards addressing complaints about the poor ride of the first E87 1 Series. It still wasn't perfect, but it was a lot better.

At around £500, adaptive M Sport suspension was a no-brainer option for many M135i buyers/leasers, and from a driving perspective they were right to make that choice too as the passive dampers are arguably a little tenough on smooth European routes. Having said that, Dan P was full of praise for the Eibach springs and passive Bilstein dampers he asked Birds to fit to his car. The low-rebound, 10mm lower setup with 15 percent stiffer rear springs and 10 percent stiffer front ones was an £1865 job (inc VAT).

The standard M135i chassis was always slightly outshone by the superlative drivetrain. Possibly to save weight, or to increase family comfort, the underbody braces that reduced back end wobble on F21 3-doors were never present as standard on the heavier 5-doors, or indeed on any of the later M140is. Fitting a set of braces to a 5-door will produce a more solid feel.
If the steering feels stiff after a period of inactivity (the car, not you), it may be a rusty universal joint on the steering column. Unsurprisingly, attempts to lubricate rust often aren't that successful. You should really be looking at replacing the joint.

Wheels, Tyres & Brakes

If you don't rate the standard BMW 436m rims (standard sizes 7.5J x 18 front, 8.0J x 18 rear, with 225/40 and 245/35 tyres) there are plenty of options. Don't be tempted by cheap aftermarket alloys though. Forged is the way to go. You could try different BMW wheels like the correctly offset 624m and 405m 19-inchers with 225/35 and 245/30 tyres. There isn't much arch room for wheel staggering.

Unless you've been living in a cave or the White House, you'll know about the harsh-riding reputation of runflat tyres on BMWs. Michelin Pilot SuperSports were the standard (non-runflat) tyre, but some owners prefer Pirelli P Zeros or ContiSport 5s. There's no spare with an M135i, just a 'Mobility Kit' which basically consists of a compressor and a bottle of foam that you hope will sort out small holes.

Cracky, pingy noises when reversing on full lock are down to tyre drag and are perfectly normal. Fitting metal dust caps to the valves is not a good idea as they will almost certainly blend in with one another in a very sociable but rather inconvenient fashion.

For track use, M4 brake pads are better at dealing with heat.


Although the M135i demands more circumspection from its driver than the relatively foolproof Mk 7 Golf R, that's the kind of characteristic that some will find more appealing.

How much will it cost to get you into one of these, then? The M135i ran for just four years from 2012 until its 2016 replacement by the M140i. As such, used prices are more a reflection of mileage and condition than age. There's not much price differentiation between 3- and 5-doors, so you can pick what you need as well as what you can afford.

Oddly (you may think, given the nature of the car), most M135is on sale have low mileages, typically between 25,000 and 40,000, and most of them will be dealer cars priced between £14,500 and £18,000. Cheaper specimens will have higher mileages.

The cheapest example we turned up on a quick online skim was a mid-term 2014 3-door in blue with four previous owners, 38,000 miles, an undocumented remap and some other mods, not all of them brilliant. Oh yes, and a Cat N certificate. Yours for just over £10,000. A more original 2013 auto in silver with red leather and 116,000 miles was up for £10,950. At the top end of the market you can pay a dealer not far short of £20k for the best post-2015 325hp cars.

The most tempting one we found was an 'appointment only' dealer's late (2016) blue 3-door with slightly grubby white leather, BMW service history, 19,000 miles and a clean MOT to July. The £12,999 price tag seemed pretty competitive: most cars of that age and price would have done 50-60k miles.

Interested yet? For more info, go to the excellent Baby BMW site, which has a dedicated M135i section - and then dip into the PH Classifieds to search for an M135i



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