Quick Facts
- Engine: 6.2L M156 V8 (naturally aspirated)
- Power: 518 hp / 386 kW
- Torque: 630 Nm / 465 ft-lb
- 0–60 mph: 4.3 sec
- Top speed: 155 mph (limited)
- Transmission: 7G-TRONIC automatic
- Available in SWB and LWB
- Production: Nov 2006 – May 2009
- Replaced by 5.5L biturbo for 2011 models
The Mercedes-Benz S63 AMG was among the top tier models of the W221 S-Class lineup. Mercedes-AMG produced two distinct versions of the S63 AMG across the W221’s production run. The model from 2006–2010 carried a 6.2-liter naturally aspirated V8, while the later 2011–2013 version switched to a twin-turbocharged 5.5-liter V8. This article covers the original 6.2L car in full, with a dedicated section on the 2011 engine change further down.
Unlike the S600 and S65 AMG which were sold exclusively in long-wheelbase, the S63 AMG was available in both standard-wheelbase (SWB) and long-wheelbase (LWB). The two configurations are mechanically identical — the only differences are in dimensions and weight, which are covered in the measurements section below.
Basic Information
The SWB uses chassis code 221.077 and the LWB uses 221.177. Production of the LWB began in November 2006, with SWB models following in February 2007. Both variants ended production in May 2009, at which point the model was refreshed as part of the wider W221 facelift — with a new engine to boot.
| Detail | Specification |
|---|---|
| Production Period | November 2006 – May 2009 |
| Make | Mercedes-AMG |
| Series | W221 S-Class |
| Model | S63 AMG / S63 AMG LWB |
| Chassis Code | 221.077 (SWB) / 221.177 (LWB) |
| Vehicle Type | 4-Door Luxury Performance Sedan |
The M156 6.2L V8 — What Makes It Special
The M156 is a naturally aspirated 6.2-liter V8, and it’s the reason this generation of S63 AMG has developed such a devoted following. Where the later 5.5L biturbo that replaced it makes more power on paper, the M156 delivers it differently — a linear, high-revving character that builds all the way to its 7,200 rpm redline. It’s an engine you have to work, and that’s precisely the appeal.
In a car like the S63 AMG, that character is something of a surprise. The W221 platform is fundamentally a luxury sedan — air suspension, long-wheelbase option, rear-seat entertainment packages. The M156 sits in that body and pulls hard in a way that feels almost at odds with the car’s refinement. That contrast is what makes the pre-facelift S63 AMG interesting.
It also has a reliability reputation that the 5.5L biturbo can’t quite match. Without turbos to service or intercoolers to worry about, the M156’s mechanical complexity is lower. The known issues — head bolt failures on early examples, valve stem seals at higher mileages — are well-documented and manageable with a knowledgeable independent.
| Engine Data | Detail |
|---|---|
| Combustion | Four-stroke gasoline, naturally aspirated |
| Engine Designation / Type | M156 E62 AMG / 156.984 |
| Fuel Type / System | Gasoline / Indirect Injection |
| Cylinder Arrangement | V8 |
| Bore / Stroke | 102.2 mm / 94.6 mm |
| Displacement | 6,208 cc (6.2L) |
| Compression Ratio | 11.3:1 |
Engine Power & Performance
| Performance | Figure |
|---|---|
| Horsepower | 386 kW / 518 hp @ 6,800 rpm |
| Torque | 630 Nm / 465 ft-lb @ 5,200 rpm |
| 0–60 mph | 4.3 seconds |
| 0–100 km/h | 4.6 seconds |
| Top Speed | 250 km/h / 155 mph (electronically limited) |
Fuel Economy
The S63 AMG is not a car you buy for fuel economy, but it’s worth knowing what you’re signing up for. The city figure in particular reflects real-world heavy traffic usage. If you’re running this car daily in urban conditions, 10 mpg is a realistic expectation.
| Fuel Data | Figure |
|---|---|
| Fuel Tank Capacity | 90 L / 23.8 gal |
| Recommended Fuel | Premium Unleaded (91+ octane) |
| City Consumption | 23.2 L/100km / 10.1 mpg |
| Highway Consumption | 10.2 L/100km / 23.0 mpg |
Transmission
The S63 AMG uses the AMG SPEEDSHIFT 7G-TRONIC, a seven-speed automatic that was a step forward from the five-speed used in the S65 AMG. The extra gear ratios give the transmission more flexibility across the rev range, which suits the M156’s high-revving character well. In Sport mode the shifts are noticeably quicker and the transmission holds gears longer before changing up.
| Transmission Data | Detail |
|---|---|
| Type | Automatic |
| Gearbox Designation | AMG SPEEDSHIFT 7G-TRONIC |
| Gear Ratios | I: 4.38 II: 2.86 III: 1.92 IV: 1.37 V: 1.00 VI: 0.82 VII: 0.73 R: 3.42 |
Steering, Brakes & Tires
| Component | Specification |
|---|---|
| Steering Type | Rack-and-Pinion |
| Front Brakes / Diameter | Ventilated Disc / 390 mm |
| Rear Brakes / Diameter | Ventilated Disc / 365 mm |
| Front Wheels | 8.5J × 19 |
| Rear Wheels | 9.5J × 19 |
| Front Tires | 255/40 ZR19 |
| Rear Tires | 275/40 ZR19 |
Measurements & Weights
The SWB and LWB share the same engine, transmission, and running gear. The LWB is 130 mm longer in wheelbase and 130 mm longer overall, which translates directly into rear legroom. If the car is primarily for the driver, SWB is the sharper-feeling choice — there is less mass to move and the shorter body feels slightly more responsive. For anyone who regularly carries rear passengers, the LWB makes more sense and was also the more commonly optioned configuration.
| Measurement | SWB | LWB |
|---|---|---|
| Wheelbase | 3,035 mm / 119.4 in | 3,165 mm / 124.6 in |
| Vehicle Length | 5,076 mm / 199.8 in | 5,206 mm / 205.0 in |
| Vehicle Width | 1,871 mm / 73.7 in | 1,871 mm / 73.7 in |
| Vehicle Height | 1,473 mm / 58.0 in | 1,473 mm / 58.0 in |
| Unladen Weight | 2,070 kg / 4,563 lb | 2,115 kg / 4,662 lb |
The 2010/2011 Engine Change: 6.2L vs 5.5L Biturbo
When the W221 received its facelift in 2009, Mercedes announced the replacement of the M156 6.2L V8 with a new 5.5-liter twin-turbocharged unit. The new engine arrived in production for the 2011 model year — so while you’ll often see “2010” cited as the changeover point (reflecting when facelift production began), a 2010 model year car still carries the M156. On paper the new engine was the better car — more power, more torque, better fuel economy. In practice, opinion in the enthusiast community has never fully settled on which is preferable.
The 5.5L biturbo produces around 525 hp in standard tune, with torque arriving low in the rev range courtesy of the turbos. It’s quicker in a straight line and more efficient on a run. But it’s a fundamentally different driving experience — turbocharged power delivery versus the naturally aspirated M156’s linear climb to the redline. Neither is objectively better; they appeal to different kinds of drivers.
From an ownership perspective, the 6.2L M156 has a slight edge in long-term mechanical simplicity. No turbos means fewer potential failure points. However, it also means no way to quietly add power through a remap — what you see is what you get. Whereas the 5.5L biturbo responds well to tuning.
| Comparison | 6.2L M156 (2006–2010) | 5.5L Biturbo (2011–2013) |
|---|---|---|
| Engine | M156, naturally aspirated | M157, twin-turbocharged |
| Displacement | 6,208 cc | 5,461 cc |
| Horsepower | 518 hp / 386 kW | ~525 hp / 386 kW |
| Torque | 630 Nm / 465 ft-lb | 700 Nm / 516 ft-lb |
| 0–60 mph | 4.3 sec | ~4.4 sec |
| Power delivery | Linear, high-revving to 7,200 rpm | Strong low-end torque, peaks earlier |
| Fuel economy (city) | 10.1 mpg | Marginally better |
| Tuning potential | Limited — naturally aspirated | Strong — responds well to remaps |
| Mechanical simplicity | Simpler — no turbos | More components to maintain |
| Used availability | Less common — shorter production | More common — longer production |
Note
Which should you buy? If you want the purer, more characterful driving experience and slightly simpler maintenance, the 6.2L is the one. If you want more used market choice, stronger low-end torque, and tuning headroom, the 5.5L biturbo is worth considering. Both are excellent cars — the choice comes down to what you prioritize.
Is the W221 S63 AMG Worth Buying?
The pre-facelift S63 AMG is one of the more compelling used performance sedans you can buy right now. Used prices have stayed relatively stable, partly because the running costs are high enough to put off casual buyers — which actually works in your favor if you know what you’re looking at. The buyers who’ve maintained these cars properly have generally done so because they care about them.
Working around classic and performance Mercedes daily, the thing I notice most about the M156-engined cars is how honest they feel. There’s no turbo masking anything — the engine either sounds healthy and pulls cleanly, or it doesn’t, and it’s usually obvious at inspection. That makes buying a used example somewhat less nerve-wracking than a heavily turbocharged alternative where issues can hide behind boost pressure.
That said, this isn’t a car to buy without doing homework. The W221 platform has known cost centers, and the S63 AMG adds AMG-specific complexity on top of that. Head bolt failures on early M156 production are worth asking about — later examples benefited from a revised bolt spec and the issue is largely resolved, but it’s still a question worth raising with any independent that’s worked on the car.
| Consideration | What to Know |
|---|---|
| Best years | 2008–2010 — later M156 production with revised head bolt spec |
| Service history | Full records essential. AMG-trained independent or dealer history preferred |
| M156 head bolts | Ask if the head bolts have been replaced on early (2006–2007) examples |
| Valve stem seals | Blue smoke on cold start at higher mileages — common, not catastrophic, but factor into cost |
| Air suspension | Check ride height is level all round — sagging corners indicate failing air struts |
| SWB vs LWB | LWB is more common and better value on the used market — SWB commands a small premium |
| vs S65 AMG | S65 is more powerful but significantly more expensive to run — S63 is the more practical performance choice |
| vs S600 | S600 is more refined and luxurious; S63 AMG is sharper and more driver-focused |
⚠ Important
The S63 AMG is not the right starting point if you’re new to the W221 platform. Get familiar with the series on an S350 or S500 first — understand the air suspension behaviour, the COMAND system, and the general cost of ownership. Then the S63 makes a lot more sense as a next step.
More About the Mercedes W221 S-Class
The S63 AMG sits near the top of the W221 range, below only the S65 AMG. To see how it fits within the full model lineup — all engines, production figures, and pricing across every W221 variant — read our complete W221 S-Class guide.
If you’re considering the S65 AMG instead, we cover the pre-facelift V12 biturbo specs in full in our S65 AMG article. And if the S600 is on your radar as the more refined V12 alternative, that’s covered in our W221 S600 guide.