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Audi’s legacy of producing fast and comfortable sedans didn’t stop with their fifth generation of mid-size sedan. The B8/8.5’s lineage can be traced back to the first fast Audi, the Sport Quattro, a homologation special designed to allow Audi to enter Group B and dominate with their all-wheel-drive. The ’80s may be long ago and Group B long dead, but the all-weather capability and outright quickness remain a staple in Audi’s lineup to this day. 

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Audi B8 & 8.5 Background Info

The B8/8.5 chassis code represents the fifth generation of mid-sized Audi sedans, coupes, convertibles, and Avants produced from 2008-2016. The model range slots above the compact "A" chassis include the A3, S3, and TT, and below the "C" chassis that consists of the A6 and S6. The S4 and S5 use VAG's MLB platform, which it shares with Audi's other sedans and the Porsche Macan. The fifth generation of S4 gets separated into two different chassis codes, the B8 and the B8.5. The B8 covers the S5 from 2008-2012 and the S4 from 2010-2012, while the B8.5 covers those same models from 2013-2016. 

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To consolidate parts and cut R&D costs, Volkswagen Group announced its plan to introduce a standardized and interchangeable bin of parts to share across its various manufacturers. They called it the MLB, German for "Modular Longitudinal Matrix," and introduced it with the B8 A5 and S5. Since then, it has included the A4, A6, A7, A8, S/Q5, and the Porsche Macan. The B8 platform was the first to use the MLB architecture with the A5 and the S5.

The B8/8.5 squared off directly against the other performance luxury sedans in its class on and off the race track. On the showroom floors and in magazine tests, the B8/8.5 was pitted against the E90 335i, W211 E63, CTS-V, and ATS 3.6. On the track, Audi flexed their B8/8.5 chassis in the DTM or German Touring Car Championship, where it competed against Mercedes and BMW, winning it all in 2013 with Mike Rockenfeller. 

When introduced in 2010, the B8 S4 was a significant step up in design than the outgoing B7. The new chassis reduced the overhangs and featured a stiffer chassis to give the new S-models significantly better agility. The B8 also saw a forced-induction V6 return to the engine bay of the S4. The outgoing 4.2L naturally aspirated V8 is a legendary engine in its own right, though more for its common problems than its performance. A reduction in cylinder count and displacement with the new 3.0t engine was balanced by adding a roots-type supercharger.

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Still, on paper, the B8 arrived with seven less horsepower than its predecessor, a theoretical step back. However, in real-world conditions, the B8 is significantly quicker than the B7. The supercharger gives the V6 a fat and flat torque curve far better than the old V8. The horsepower, too, is carried out across a broader curve, giving the B8 more available power.

Engineers placed the 3.0t in its new S4 and S5 Cabrio but left the 4.2L V8 in the S5 Coupe until 2013 when the B8.5 arrived. 

Audi sold over 57,000 B8/8.5s by the time their production ended in 2016. Since then, 3.0t-equipped S4s and S5s have become performance staples in the used market. Their reliable power plants are easily tunable, producing significantly more power over stock with a few modifications. In true Audi fashion, they are wrapped in a roomy and comfortable chassis that can confidently power through harsh weather conditions. 

 

What Are The Differences Between The Audi B8 & B8.5 S4 & S5?

The original B8 chassis debuted in 2008 and was getting long in the tooth by 2012, so Audi introduced the facelifted model, the B8.5, for the 2013 model year. The B8.5 featured mostly external and internal aesthetic changes to the S4 and S5. These, combined with a few mechanical updates, extended the life of the chassis until the new B9 was ready.

The best way to differentiate the two is by the front bumper/grill and the lights. The B8 uses a mostly rectangular headlight with the inner LED strip reminiscent of the R8. The B8.5 uses a more complex shape with a more aggressive and extensive LED arrangement. Between the headlights, the B8 uses an upside-down trapezoidal grille that takes up 80% of the space available. Audi didn't change the updated grill too much, smushing the upper corners into two extra small and flat sides, creating a very uneven hexagon. 

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Below the headlights, you'll find different fog lights. The early design uses a round fog light, while the facelift uses rectangular fog light with a slanted inner side. Around the back, the updated taillights feature a slightly different inner corner along with a change in the LED pattern matching the headlights. Additionally, the hood and bumper are different to accommodate the change in grill and lights. Still, they are very similar to the parts they replaced.

Mechanical updates varied between models. The S5 Coupe finally ditched the aging 4.2L FSI V8 in favor of the 3.0t that the rest of the range used. Along with the V8 went the optional six-speed Tiptronic transmission in favor of the S-Tronic DSG that the rest of the range also used. The only mechanical change that all of the B8.5 "S" models received was switching over to electrically-assisted power steering, ditching the hydraulically-assisted setup. 

Inside the cabin, the S4/S5 received a new flat-bottomed steering wheel as standard, along with various trim pieces and interior bits. A revised infotainment and navigation system also found its way into the B8.5. 

 

Audi S4 & S5 Engines (B8 & B8.5)

4.2L V8 (CAUA)

The B8 S5 uses the naturally-aspirated 4.2L V8 developed alongside the R8's first power plant. The "Comfort" variant of Audi's V8 developed for the Q7 and S5 uses an aluminum block and cylinder heads with direct fuel injection to produce 354 horsepower and 325 lb-ft of torque. S5 buyers could spec either a six-speed manual or the six-speed automatic, called the Tiptronic. The 4.2L V8 was the go-to performance engine for Audi during the '00s, with its multiple variations appearing in the R8, B7 S4, B7 RS4, and C5 S6 before the B8 S5. Though by 2013, its size and displacement weren't necessary, the replacement for displacement became easy and reliable with forced induction. 

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While outdated compared to the 3.0t, the last of the V8s is relatively reliable. Audi fixed most of the engine's minor issues, making it significantly more reliable than its previous iterations. However, they couldn't change the placement of the timing chain, so any issues related to that will still necessitate an engine removal. Proper maintenance done at the specified intervals has proven to be the best thing for the CAUA V8. Its most essential service items being spark plugs, ignition coils, and regular oil changes every 5,000 miles. Because of the nature of DFI, they also greatly benefit from having their intake tracts cleaned of carbon buildup. 

If you're after the theatre of driving rather than outright pace, the V8 has some advantages. Its power delivery and V8 howl are almost guaranteed to deliver a grin so wide it'd make the Joker blush. Aftermarket tuning options are limited for the V8, however. Freer-flowing intake and exhaust components are the most accessible sources of more power and noise. However, the increase of the former is limited. Several companies make centrifugal and roots blower kits for the 4.2L, but their average going rate is about $6,000. Arguably the best modification for them is the addition of a dipstick. Audi uses an electronic sensor to read the oil level, but installing the dipstick makes it much easier to check the oil level than digging through the MMI.

Technical Specs:

  • Engine Type: Naturally-Aspirated 90° V8
  • Displacement: 4.2L
  • Horsepower: 350 hp @ 7000 RPM
  • Torque: 325 lb/ft @ 3500 RPM
  • Compression Ratio: 12.5:1
  • Max RPM: 8250
  • Cooling: Water-cooled
  • Induction: Two-Stage, Variable, Magnesium Intake Manifold
  • Injection: Direct Fuel Injection
  • Valvetrain: Dual Overhead Camshafts with variable intake and exhaust timing
  • Valves: 32 Valve
  • Bore x Stroke:  84.5mm x 92.8mm (3.33in. x 3.65in.)
  • Timing Chain: 4-Chain Configuration
  • Oiling System: Wet-sump
  • Engine Oil Capacity: 8.8L (9.3 qt)
  • Required Octane: Premium Unleaded (91+)

 

3.0t V6 (CAKA/CCBA/CREC)

 

The 3.0t V6 was the new kid on the block when the B8 S4 debuted and is still the current go-to performance engine for the B9 S4/S5. It uses an AluSil engine block and aluminum cylinder heads combined with direct fuel injection and a roots-style supercharger to produce 333 horsepower and 325 lb-ft of torque. S4 buyers could spec either a six-speed manual or the seven-speed S-Tronic DSG. Replacing the aging V8 with a genuinely reliable engine capable of good power numbers was a must for Audi at the start of the 2010s, and the 3.0t hasn't disappointed. 

The 3.0t doesn't have any significant area of concern. Superchargers rarely fail but are costly to replace if they do. Some of the early engines had oil consumption issues but were fixed with an updated PCV. The water pump and thermostat do like to leak when they get near their service intervals. They sit below the supercharger, causing the coolant to pool below it as it weeps. That'll cause a strong and sweet smell from the antifreeze. Lastly, the engine mounts do occasionally fail, hydraulically or electronically. Like the V8, proper maintenance is the key to a healthy 3.0t. The most important service items being spark plugsignition coils, and regular oil changes every 5,000 miles. Because of the nature of DFI, they also greatly benefit from having their intake tracts cleaned of carbon buildup. 

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However, arguably the most significant benefit of the V6 comes when more power is needed. The factory ECU mapping is very conservative from the factory to provide the best reliable power and fuel economy mix. But, a simple ECU flash can pull nearly another 80 horsepower and 35 ft-lbs of torque from it. With more parts, like a different supercharger pulley, fueling upgrades, and a freer-flowing exhaust system, the 3.0t can push out over 500 horsepower on the stock internals. Tune it right, and it'll deliver better fuel mileage than the V8, too. The 3.0t will wipe the floor with the V8 for significantly less money. 

Technical Specs:

  • Engine Type: Supercharged 90° V6
  • Displacement: 3.0L
  • Horsepower: 333 hp @ 5500-7000 RPM
  • Torque: 325 lb/ft @ 2900-5300 RPM
  • Compression Ratio: 10.3:1
  • Max RPM: 7300
  • Cooling: Water-cooled
  • Induction: Roots-Style Eaton Supercharger (0.8 Bar, 11.6 PSI)
  • Injection: Direct Fuel Injection
  • Valvetrain: Dual Overhead Camshafts with variable intake and exhaust timing
  • Valves: 24 Valve
  • Bore x Stroke:  84.5mm x 90mm (3.33in. x 3.54in.)
  • Timing Chain: 4-Chain Configuration
  • Oiling System: Wet-sump
  • Engine Oil Capacity: 6.8L (7.2 qt)
  • Required Octane: Premium Unleaded (91+)

 

Audi S4 & S5 Transmissions & Driveline (B8/B8.5)

Three transmission options were available throughout the B8/B8.5 run. The 0B4 6-speed manual transmission was the standard option for the Coupes, while the two-pedal transmission options differed. Only the B8 S5 Coupe with its V8 had the Tiptronic six-speed automatic as an option. The seven-speed S-Tronic DSG became the only other choice once Audi retired the V8 in favor of the 3.0t. The other V6 models, the B8 S5 Cabriolet and the B8 S4 had the DSG from the jump. 

0B4 6-Speed Manual

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It's tough to go wrong with a row-your-own gearbox, and the 0B4 doesn't disappoint. It's a traditional H-pattern, fully synchronized transaxle that uses a hydraulic clutch system. Both simpler and lighter than both two-pedal options, the 0B4 is a trouble-free choice. It was the only transmission offered from the start of the B8 through the end of the B8.5, so there are quite a few cars out there using them. Like any other manual in a used car, they're as good as their previous owner treated them. Unfortunately, not everyone can properly drive a manual transmission, so avoid anything with transmission issues. 

With that said, the 0B4 doesn't have many faults. They will take abuse at the stock power level and hold up to about 450 horsepower or 380 ft-lbs of torque where the stock clutch will start to give up. Higher mileage transmission may begin to weep fluid; look around the output flange seals and the driveshaft seal. Beyond that, though, regular maintenance will keep them working correctly. According to Audi, the fluid needs replacing at 50,000-mile intervals. 

Building the 0B4 to hold considerable power requires a new clutch and a single-mass flywheel. Clutch kits that include the pressure plate are widely available and carry prices around the $1200 range. However, the flywheel is tricky. The 0B4 requires a unique flywheel, unlike any other Audi product. Lightweight single-mass units do exist but will cost about the same, if not more, than an upgraded clutch kit. 

Factory Performance:

  • 3.0t 0-60: - 4.9 seconds 
  •  ¼ mile: - 13.4 seconds
  • 4.2 V8 0-60: - 4.8 seconds 
  •  ¼ mile: 13.4 seconds

 

ZF 6HP28 Six-Speed Tiptronic (Automatic)

For whatever reason, Audi didn't mate their 4.2L V8 up to their DSG box and instead paired it with their Tiptronic. Built by ZF, the Tiptronic is a conventional torque-converter automatic transmission-equipped only to the B8 S5 Coupe. While not as advanced as the DSG, the Tiptronic is a solid performer in its role. Shifts are smooth and relatively quick while being as responsive as the best torque-converter boxes of that era. Automatics have always been popular, so finding one shouldn't be an issue.

The manual excels at keeping the driver engaged. The Tiptronic shines as a weekend cruiser or a highway eater. Pure aggression isn't its forte; it's more grand tourer than sports racer. However, that doesn't mean it can't keep up with its competition. The BMWs of that era use a very similar automatic box also built by ZF. It'll get the S5 up and moving very quickly at stock power levels, though it isn't made for anything more than that. 

The best Tiptronics have a complete service history documenting the necessary fluid and filter changes every 40,000 miles. Skipping on those changes allows gunk and debris to accumulate in the valve body, causing slipping and hesitation. Finding one in proper working order is paramount to keeping a happy bank account as any major repairs will be costly. Have the TCU codes checked to ensure that nothing is going on internally, and listen for any grinding or slipping. Avoid anything with issues present.

Factory Performance:

  • 4.2 V8 Tiptronic 0-60: 5.1 seconds 
  • ¼ mile: 13.6 seconds

 

DL501 S-Tronic Seven-Speed DSG

 

In terms of speed, this is as good as it gets from Audi. Rivaling Porsche's PDK, the S-Tronic DSG is a stout and reliable box capable of holding significant power. It is arguably the most common gearbox option, too, as the only choice for the S5 Cabriolet, available throughout the S4's production and appearing in the S5 Coupe after switching to the 3.0t. Its dual-clutch system makes it quicker and more accurate than the 0B4. Plus, its ability to shift itself through the TCU makes it an outstanding choice for daily driving. Using only two pedals, too, makes it as easy as a traditional automatic in traffic.

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There aren't any faults with the S-Tronic. Like the other boxes, maintaining the DSG at its proper 40,000-mile interval will lead to its best performance and lifespan. Each service is a fluid replacement and filter change, and they can be on the pricey side relative to average service costs. Early S-Tronics in the B8s occasionally had internal control units fail, although Audi eliminated the issue from the later gearboxes. Called Mechatronics, those parts will ring up right around $500 from FCP Euro.  

Tuners and Audi performance shops have proven that the DSG can hold significant power over the stock levels while maintaining factory driveability. It offers complete manual shifting and launch control from the factory. With upgraded clutches and a remapped TCU, it'll hold upwards of 800 ft-lbs of torque without breaking a sweat. It is the best blend of performance and everyday driveability, bar none. 

Factory Performance:

  • 3.0t S-Tronic 0-60: 4.7 seconds 
  • ¼ mile: 13.2 seconds

 

Driveline

All three gearboxes send their power through a center differential that splits it and sends it to the front and rear wheels. The B8 chassis uses a Torsen-style differential, and the B8.5 chassis uses the Audi Crown Gear Differential. The Crown Gear diff is a mechanical self-locking differential capable of changing its power-split quicker than the old Torsen. It can send up to 70% of the power to the front axle or 85% to the rear, depending on which has the most traction. 

 

Audi S4 & S5 Notable Options (B8/B8.5)

Audi gave the B8 and B8.5 a large list of options to choose from like any European Luxury manufacturer. Regardless of trim level and options, all models came equipped with a sunroof, leather sport seats, and multi-zone climate control. Beyond that, each model received either the Premium Plus or Prestige trim. The Premium Plus trim was the lowest trim level but could be optioned with all of the components that made up the higher Prestige trim. Those options include the Audi MMI Navigation Plus Package, Audi Adaptive Light, Audi Advanced Key, and Audi Side Assist. Every model was optioned differently, and finding one with all the right options may be difficult. Forgoing one for another is almost a guarantee while looking at used models.

Sports Differential

Both the B8 and B8.5 had the "Sport Differential" as an option. That option replaces the rear differential with a unit capable of torque vectoring. Through the use of various sensors, the car determines which of the rear wheels the torque would benefit from the best in terms of performance. It then splits the power between the rear wheels to maximize acceleration, grip, and control through the corner. This is a fantastic option to have for a daily driver that will see some track time. 

Black Optics Package

One of the signature details that set the "S" cars apart from their lower spec siblings are the satin aluminum-finish mirror caps, window trim, and grille surround. Audi offered the black optics package for a more aggressive and sinister look. It replaces the window and grille trim with black pieces and changes the mirror caps to body color. Not too many were spec'd with this option, so finding one might be tricky.  

Alu-Optics Package

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Another trim package for the exterior, it's the opposite of the black optics. Instead of removing the aluminum-look trim, this package changes the side blades mounted on the skirt, appearing in the same aluminum look as the trim. It also replaces the "V6T" badging on the fender with one that reads "Supercharged."

 

How Much Does A Used Audi B8 & B8.5 S4 & S5 Cost?

Depreciation is the second-hand market's best friend. The earliest B8s have been around for the better part of 13 years, and many have seen plenty of miles. The best examples still bring a fairly high amount of money. But you can find examples cheaper than a new Corolla with good service history and higher miles. It isn't hard to find a B8 with a bunch of miles and some sketchy service history. Thankfully, the B8.5s are still new enough that almost all are taken care of. EIther model with either chassis is a good buy for a fast daily commuter, depending on how much you spend. 

Used Audi S4/S5 Pricing (B8)

  • S5 2009-2012
    • $8000-$12000 Low-end
    • $15,000-$22,000 Average to High
  • S4 2010-2012
    • $10,000-$15,000 Low-end
    • $16,000-$25,000 Average to High

Used Audi S4/S5 Pricing (B8.5)

  • S5 2013-2016
    • $22,000-$37,000
  • S4 2013-2016
    • $18,000-$32,000

 

How reliable are the B8 & 8.5 Audi S4 & S5?

The B8 and B8.5 chassis S4 and S5 are generally reliable and not just in Audi terms. The 3.0t engine holds up very well to abuse at the stock power level and can handle much more than that even with the stock internals. Chassis and brake issues don't really exist for this chassis either. 200,000+ mile B8s exist and are well documented online by their owners, having received proper maintenance with quality parts. Lacking service and maintenance is the downfall to these Audis.

The early B8 S4s equipped with the DSG had some issues with their transmission electronics that were later resolved by revised parts. The Tiptronic in the B8 S5 Coupes will handle higher miles but won't last as long as the DSG. Ensure the Tips shift smoothly with no hesitation, slipping, or grinding while test driving. Be prepared to spend a significant amount of money to fix them if they go wrong.

If you go for a higher mileage V8 S5, listen for any rattling on startup. The timing chain guides and camshaft chain guides wear and eventually need replacement. That replacement job is a huge undertaking and isn't DIY friendly as the engine needs to be removed from the engine bay just to access them. 

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The best thing you can do to a possible B8/8.5 purchase is to have it inspected by a dealership or independent shop beforehand. Any seller who isn't hiding issues should agree to it. Assume those who do object to be hiding something and reconsider your purchase. Any repairs it might need won't be cheap. High-performance Audis are engineered to tight tolerances, and their parts aren't the cheapest. However, doing minor services and maintenance yourself is a great way to keep those costs down, especially if you take advantage of the FCP Euro Lifetime Guarantee. 

 

Audi S4 & S5 DIYs (B8 & B8.5)

How To Replace The Water Pump & Thermostat On Your B8/B8.5 Audi S4

How To Replace The PCV On A B8 Audi S4 (Audi A7, S5, & SQ5)

How To Replace Audi S4 Supercharger Oil (Audi B8/B8.5 S4, S5, Q5, Q7, & More)

How To Change The Oil In An Audi S5 (Audi B8/B8.5 4.2 L V8)

How To Replace Audi Spark Plugs & Ignition Coils (Audi Q5, S4, Q7 B8/B8.5 & More)

How to Replace B8 Audi S4 Rear Brake Pads & Rotors (Audi S4, S5, & SQ5)

How To Perform An Audi SQ5 Oil Change (Audi B8/B8.5 A4, A5, S4, S5, & More)

How To Walnut Blast Intake Valves On An Audi 3.0t Engine

 

Audi S4 & S5 Modifications (B8 & B8.5)

03_Bilstein Sport shock kit B8 S4 S5 FCP Euro

There are countless mods for the B8 & B8.5 S4/S5 that the community often installs on their car. To read more about our recommendations, read our Audi S4 & S5 Must-Have Mods article, here

If you have any questions about the B8/B8.5 Audi S4 or S5, be sure to leave them in the comments below. For more Audi DIYs, guides, and news, visit audi.fcpeuro.com or check back here on the blog. 

 

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Written by :
Christian Schaefer

Owner of a flat-six swapped 1998 Impreza 2.5RS and a 1973 Porsche 914. Horizontally opposed views, only.


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