The BMW M4 and M3 high performance coupe and sedan occupy a unique niche, blending supercar-rivaling speed with relatively practical four seat luxury. Packing over 425 horsepower from their high-revving straight six engines, these "M" designated Ultimate Driving Machines rightfully command serious money on the used market. However, complex performance cars inevitably suffer more problems. This comprehensive buyer‘s guide from a fellow BMW enthusiast explores the most common issues on 2014-2020 M4 and M3 cars to ensure your pre-owned purchase stays exhilarating, not expensive!
The High-Strung S55 Powerplant
Motivating the M3 sedan and M4 coupe models is BMW‘s S55 – a specially tuned variant of their regular 3.0L N55 twin turbo inline 6 cylinder. Output stands at 425 hp and 406 lb-ft torque in standard trim. While based on a sturdy foundation, the hot-rodded S55 does suffer more teething problems:
Crank Hub Wear
This small part connects the crankshaft to the flywheel, helping manage the engine timing. However early S55 crank hubs featured subpar metal that wore down rapidly, causing the timing chain to slip. The result? A check engine light followed by extremely expensive repairs often terminating in a full rebuild or replacement.
BMW actually issued an extended warranty for affected 2014-2015 cars. However that coverage ends at 50k miles – still well within the working life of these performance engines. Replacing the hub proactively costs around $1500 but saves way more down the line. Every S55 should receive this upgraded part installed.
Oil Leaks
Another common headache comes from various external oil leaks. Typical problem areas include:
- Oil filter housing gasket
- Valve cover gasket
- Oil pan gasket
The valve cover leak especially annoys owners since the oil drips directly onto the hot exhaust pipes below, smoking noticeably. Resealing the valve cover runs $800 while the more extensive oil pan gasket replacement often reaches $2000+ in labor costs.
Tapping Noises on Cold Start
Excessive tapping from the valvetrain on initial cold starts often indicates worn exhaust camshaft lobes in early production M3 and M4 vehicles. BMW revised the metallurgy and Timing chains help mitigate this – but still prove insufficient long term. Once you hear noisy tapping the cam itself needs replacement – a $2000+ job.
How The S55 Improves on the N55
Interestingly, once BMW resolved the premature issues above, the S55 powerplant actually improves on the regular N55 engine thanks to shared components:
| Specification | N55 Engine | S55 Engine |
|---|---|---|
| Displacement | 3.0 L | 3.0 L |
| Horsepower | 335 hp | 425 hp |
| Torque | 332 lb-ft | 406 lb-ft |
| Tune Potential | 400+ hp | 700+ hp |
This indicates great modification potential. With just bolt-on aftermarket upgrades like intakes, downpipes and ECU tunes, the S55 reliably reaches over 500 wheel horsepower! Just be sure to address known faults early on.
So while the S55 stumbles out the blocks in early cars, properly maintained it serves an enthusiast owner well long term. Let‘s explore the transmission and driveline next.
Proven BMW Transmissions
The M4 can be equipped with either a 6-speed manual gearbox or a 7-speed M-DCT automated dual clutch transmission. Both handle the onslaught of torque capably:
Manual Gearbox
The traditional stick shift pairs well with the high revving engine for maximum driver engagement. Clutch feel stays consistent unless abused on drag strips. Expect 60-80k trouble free miles before replacing these wear items:
- Clutch Disc + Flywheel – $1800
- Shifter Cables – $120
- Differential Fluid – $150
M-DCT Transmission
This 7-speed automated dual clutch transmission provides lighting fast shifts when left in automatic mode. Paddle shifters allow manual control when desired. Holding 416 lb-ft of torque, the BMW M-tuned DCT rarely suffers mechanical issues provided you change the fluid every 40k miles:
- DCT Fluid Change – $350
- Clutch Packs – $4000 (if worn prematurely)
The electronically controlled nature means sensors can fail, but these prove relatively inexpensive to diagnose and replace. Some owners complain of jerky low speed shifts – especially when cold. Overall though, both transmissions suit the hair-raising performance. Now let‘s explore some other key areas.
Gremlins in Electronics
BMW packs the M3 and M4 with cutting edge technology – but this does lead to more problems as systems age:
Faulty Bluetooth Antenna
The shark fin antenna on the trunk lid facilitates keyless entry and phone pairing. However it seems the glue deteriorates in sunlight leading to Bluetooth dropouts. Fixing involves replacing the entire antenna assembly.
iDrive Controller Failures
The rotary iDrive dial controls the infotainment screen. After years of use, the knob sensor wears out resulting in a non-responsive spin. While the replacement part stays inexpensive, coding it to the vehicle‘s VIN requires expert technician knowledge.
Assorted Sensor Problems
Various other sensors linked to the adaptive suspension, active differential, stability control and more can sporadically fail. This necessitates connecting a diagnostic scan tool to decipher fault codes and pinpoint the exact issue component.
These electronic issues don‘t comprise safety, but certainly undermine the sense of technical polish expected in top tier BMWs. At minimum test all accessories work during your test drive. Extended warranty coverage also provides peace of mind too.
Wear and Tear Considerations
While M4 and M3 chassis dynamics excel on twisty backroads, the ride quality and interior appointments feel lacking considering the original $65k+ pricing:
Dashboard Rattles
Many owners complain about annoying rattles emanating from the dash over bumps. The culprit? Overly cost conscious construction with hollow plastic panels. Disappointing in a $60k car. Carefully listening when driving over uneven surfaces.
Bolster Wear
Due to repeated lateral sliding during hard cornering, the side bolsters on both front seats tend to wear quickly. After just 1-2 years you may spot smoothing and creased leather. This not only looks scruffy but also provides diminished lateral support, unless you opt for new seat upholstery.
Soft Paint
Perhaps the most frustrating issue comes not from an actual fault, but rather inadequate paint durability from the factory. Chips and swirl marks appear easier than on a comparable Audi or Mercedes. While not safety related either, this still annoys owners aiming to keep their car pristine. Expect to invest in paint protection film and regular ceramic coatings.
Let’s summarize the key running costs.
Maintaining These Powerful Machines
While no means as prohibitively expensive as other German performance marques, M car ownership still runs pricier than an average 3 or 4 Series:
As illustrated above, budget around $2000 annually for essential maintenance like:
- Brake Pads & Rotors – wear faster with repeated hard stops ($1300 every 20k miles)
- Tires – soft summer performance tires last 15k miles ($1200 per set installed)
- Fluid Changes – critical for protecting driveline components ($350 yearly)
- Miscellaneous – wipers, filters, spark plugs, etc ($500)
While M cars share everyday parts with regular 3 and 4 series, items stressed by high performance wear out faster. Given the $55/hour labor rate, repairs cost noticeably more than an economical Civic. Things add up!
Insurance & Fuel
With 100+ mph top speeds, insuring these BMW‘s proves understandably expensive, especially for younger drivers. Likewise the 15 mpg city rating means filling its 16 gallon tank runs almost $100 a pop.
Out of Warranty Engine Repairs
While the S55 powerplant proves largely robust, should something catastrophic fail after the 50k mile mark, you risk $5000+ repair invoices. Even a simple turbo replacement runs upwards of $2800 – just for parts!
This highlights why you MUST get any prospective purchase pre-inspected along with considering an extended warranty if still relatively low mileage.
Verdict – The Ultimate BMW Sports Machine
Like any complex performance automobile, the F80 M3 and F82 M4 come with their fair share of potential issues highlighted here. However, the vast majority of secondhand owners enjoy years of exhilarating, trouble-free driving when buying the best examples and properly maintaining them. Just be sure to heed the checklists below:
During your test drive
✔️ Thoroughly inspect paint condition
✔️ Note dashboard rattles over bumps
✔️ Check bolster wear on both front seats
✔️ Listen for odd engine noises when cold
✔️ Review electronics functionality
Before purchase
✔️ Get a pre-purchase inspection (PPI)
✔️ Run vehicle history report for accidents
✔️ Consider extended warranty for peace of mind
After taking delivery
✔️ Change differential and transmission fluid
✔️ Upgrade crank hub if early production year
✔️ Detail paintwork and apply ceramic coat
Finding a cherry condition M4 or M3 with ideal maintenance history means less hassles long term. You can then focus purely on enjoying these Ultimate Driving Machines as BMW intended. Never forget the smiles per mile!
Which would you choose – the coupe or sedan? Let me know in the comments your experiences living with BMW‘s M models!