Launched in 2009, the S4 was a rare foray into supercharging for Audi. Here's how to get a good one
By Tony Middlehurst / Thursday, November 5, 2020
- Available from £9,000
- 3.0-litree V6 supercharged, all-wheel drive
- Not blemish-free mechanically
- Ride can be a tad nobbly
- Careful maintenance is essential
- Low-mile post-'12 facelifters are your best bet at £15-£20k
Search for an Audi S4 here
When a manufacturer has established a reputation for sporting excellence based on good-sized normally aspirated V8s, you know there's going to be massed groans when they announce the end of the line. That was the situation facing Audi's PR folk in the mid Noughties when they had to reveal that the S4 for the 2010s would be powered by a small 3.0 V6 rather than the thundering 4.2 V8 of the previous B7 model. In terms of the ongoing pocket battleship war against BMW and Mercedes who were both continuing with V8s in their M3 and C63 AMG, this was not what the Audi fanbase wanted to hear.
Audi's downsizing gamble was based on a combination of force majeure on the emissions front and their interest in creating a better daily driver, and when the B8 production line started in November 2008 it looked like they'd pulled it off. In terms of emissions, the manual 3.0 saloon was 94g/km cleaner than the V8. On power, supercharging the B8's TFSI six had almost entirely compensated for its loss of two cylinders and 1.2 litres of displacement: it produced 329hp versus the B7 V8's 339hp.
All-wheel drive featuring a Torsen centre differential (and the new option of an Audi Sport rear diff) gave 40/60 torque distribution in normal driving with up to 100 percent available for the rear and 80 percent for the front, depending on road conditions, but what really made the new S4s' performance super-accessible was the wider torque spread of the forced induction engine. The old V8 pumped out 302lb ft at 3,500rpm, with its power peak not arriving until 7,000rpm. The V6's 325lb ft was available all the way from 2,900-5,300rpm, and just 200rpm after that you were gently lifted onto a 1,500rpm-wide peak power plateau. Effectively you had serious performance from 2,900rpm to 7,000rpm.
A small weight loss of 10kg in the new saloon and 15kg in the Avant closed the power to weight ratio gap between the old and new S4s to just 5bhp/tonne (199hp/tonne for the B8 versus 204hp/tonne for the B7). It was a pity that the V6 didn't sound or even feel especially quick relative to the V8, but there was no arguing with the figures. Despite giving away almost 100hp to the M3, the S4 gave very little away to the sportlich BMW on the 0-62 time, which for the manual S4 saloon was reduced from 5.6sec to 5.1sec, with an even bigger time saving for the manual Avant (from 5.8 to 5.2). On a side note, the S4 convertible of previous generations had been dropped, that fast fresh-air role being taken on by the S5 Cabriolet.
Although a twin-clutch gearbox will today routinely knock half a second or so off the 0-62 time of any quick German car, when the B8 S4 came out in 2009 Audi's official testing person did manage to hustle the 30-35kg lighter 6-speed manual through the traps in less time than was needed by the S tronic version. He or she would have been using slightly more petrol in the process though, because even in 2009 DCT transmissions were starting to deliver the sort of fuel efficiencies that we now take for granted. The B8 S tronic saloon's combined fuel consumption figure of 30.1mpg was more than 8mpg better than that of the old B7 Tiptronic, and indeed of the M3.
An 8.5 facelift was released in 2012 bringing the new A4 range look, some modernising interior mods and electromagnetic steering, taking the B8 up until the 2015 Frankfurt show when Audi unveiled the fifth (B9) generation of the A4. It had a more chiselled look and, in the S4, a turbocharged 349hp version of the 3.0 V6 mated to an 8-speed auto. This drivetrain brought the S4 saloon's 0-62 time down to 4.7secs and knocked the parasitic losses of supercharging on the head once and for all.
Nerd fact: the S4 has always worn 'V6T' badges on its body panels even when it was supercharged rather than turbocharged. Apparently it's nothing to do with the 'T' in 'TFSI' standing for turbo fuel stratified injection. Audi says that 'T' in 'V6T' stands for either kind of forced induction, which sounds a bit lame, but evidently they didn't want any more 'S's on the car other than the one before the '4' (or 5 in the S5). When the 8.5 came out you could get it with a 'supercharged' badge. We're not sure if you can still get original badges from Audi dealers but copies are of course available.
The B9 went on sale in 2016 and was taken off the market in late 2018 to avoid the aggro of re-certifying it for the WLTP emissions reforms. Even 50,000-mile B9 S4s haven't really dipped below the £23,000 mark yet, and £25k is a more realistic starting point for them, but B8 S4s can be picked up for the piffling sum of £9,000. They're the models we'll be focusing on today.
SPECIFICATION | AUDI S4 (B8)
Engine: 2,995cc V6 supercharged
Transmission: 6-speed manual or 7-speed S tronic auto, all-wheel drive
Power (hp): [email protected],500-7,000rpm
Torque (lb ft): [email protected],900-5,300rpm
0-62mph (secs): 5.1/5.3 (saloon man/auto), 5.2/5.4 (Avant man/auto)
Top speed (mph): 155 (governed)
Weight (kg): 1,685 (saloon auto), 1,735 (Avant auto)
MPG (official combined): 29.1/30.1 (saloon man/auto), 28.5/29.4 (Avant man/auto)
CO2 (g/km): 225/219 (saloon man/auto), 229/224 (Avant man/auto)
On sale: 2009 – 2016
Price new: £39,000 (£40,000 Avant)
Price now: from £9,000
Note for reference: car weight and power data is hard to pin down with absolute certainty. For consistency, we use the same source for all our guides. We hope the data we use is right more often than it's wrong. Our advice is to treat it as relative rather than definitive.
ENGINE & GEARBOX
Twin-rotor Roots-type superchargers like the one in the S4 bring a special character to a car, even if for many PH types that character is unlikely to trump that of an NA V8. If you fall into that rortmungous demographic the B8's V6 might be an aural disappointment, but if you're less bothered about big noise than you are about making big progress then the S4 should definitely be on your short list.
The 3.0-litre engine was based on the 3.2 FSI used in some 2006-09 A4, A5 and A6 models. It is a deceptively effective unit and a solid one too with a generally good reputation for reliability, but few cars are spotless and the B8s were no exception.
Early ('09 and '10) cars had a fair bit of bother with their water pumps and thermostats. If the pump blew, sudden and rapid water loss was the result. If the car you're looking at has a plastic pump housing under the blower then somehow it's escaped the recalls that eventually replaced it with a metal version.
Thermostats would stick closed. It's not as easy to check the status of your 'stat as it is the water pump as it sits inside its own housing. Here's where a comprehensive service history with a written record of all recall work carried out is worth its weight in gold. Replacing the stat yourself isn't that hard. Best plan is to do the stat, temp sensor and expansion tank all at once, along with a coolant flush. Aftermarket tuning firms sell these cooling system refresh kits for £100 or so.
Slow and hard to trace coolant loss can afflict many Audis. Sometimes this was down to oil cooler failure (not exclusive to the S4). Not unconnected to this, 3.0T engines built after mid 2012 were fitted with a lower-pressure positive crankcase ventilation valve. This was meant to help improve oil consumption, which wasn't as heavy as it could be with the first-generation 2.0T TSI engines but which could still be as much as a pint every 800 miles. Early 3.0s had old-style oil pressure switches that could fail and limit the engine to 4,000rpm, cured by an uprated switch.
Lessons were learned on the 2.0T TSI's faulty ignition coils and injectors (sympathy to anyone who ran a 2.0T!), so neither of these were as problematic on the 3.0, but the coils do need to be extracted properly and rich readings from stuck-open injectors are not unknown on the 3.0. Spark plugs run on a 55k mile/5 year service schedule, and are best replaced by original equipment items.
Carbon buildup is a thing with TFSI engines. Any slight roughness at idle is a good indicator of that. Walnut shell blasting allows the valves to reseat properly and can liberate some lost horsepower but it will likely cost you more than £300.
Lower crank pulleys would be an issue on early cars if the rubber delaminated and set up a wobble. That could lead to ruinous damage up to and including a broken crank. Aftermarket crank pulley upgrades were considered to be a highly desirable preventative move. Aftermarket supercharger drive pulleys work well on the 3.0 TFSI too by increasing the rotational speed of the blower. A stage 2 ECU upgrade with a dual pulley setup can hoist power and torque to beyond 460hp/460lb ft. A more modest stage 1 remap will get you to 400.
Deleting the resonator from the exhaust system is a popular mod for enhancing the engine tone, although generically speaking this sort of mod can trigger CEL warnings and codes or even create catalytic converter trouble. Them as do do res deletes on their motors (not just S4s) reckon that MOT inspectors have no problem with them, but that is not an official PH fact.
The switch to turbocharging in the 2015-on B9 was a clear indicator that superchargers were no longer right for cost- and health-conscious times. If you drive a B8 very gently you might hit the official mpg figure of 30mpg, but it'll be 20mpg or less if you drive in a more hoony fashion, and something between those two figures in normal use.
Manual B8 S4s are quite rare in the UK, and creaking clutches were an issue, but the S tronic transmission's well judged ratios and the speed with which they can be engaged (in Sport mode anyway) will have even the most ardent manual trans fans stroking their virtual beards. Make sure that the paddles manually select gears as they should though and for your wallet's sake keep on top of the servicing.
The mechatronic unit, which is basically the clutch, is a sealed unit that has acquired something of a negative rep. Jerky or delayed changes, clunks, hard downshifts, weird smells and oil leaks are all symptoms of impending failure. The unit alone is around £1,000, with a whole gearbox overhaul at least doubling that cost, so make sure that the paperwork for a car you're looking at includes records for regular S tronic servicing (every 35-40,000 miles). Depending on how they've been filled, these gearboxes can often be running around a litre light.
Grip and traction are both top notch with or without the £2,000 Drive Select option that allowed the driver to choose between Comfort, Auto and Dynamic settings for the throttle map, steering weight, dampers, ESP and electronic rear differential. Switch off the ESP and you should be able to detect power being directed to the outside wheel rather than the ESP applying braking force to the inside one. Dynamic opens up a whole new world of power sliding. There was a tech bulletin about failure of the adhesive used for diff flange seals.
It would be an overstatement to say that this was the car that silenced all the Audi doubters when it came to suspension and more particularly steering. The A4's multi-link suspension design was carried over to the S4, albeit with the lowering and stiffening that's normally applied to sporting derivatives. Although damping action was noticeably more sophisticated in the B8, the inherent stiffness of the suspension meant that the ride quality was only middling on pocky British roads. Eibach springs are a common upgrade.
B6 S4s had a reputation for troublesome steering, with more than a few owners reporting looseness or clicking. The electromagnetic steering that came in with the 2012 8.5 facelift brought its own problems of wandering and a notchiness or resistance to self-centring that some described as a bit like that repulsion you get when you try to force together identical poles of two magnets. The problem (which seemed to be worse in cold conditions) was most associated with 2013 cars but some '14 and '15 cars also had it.
It's to do with the Driver Steering Recommendation (DSR), a feature of the ESP system. Sensors detected when the car was starting to skid and the steering's electronic control unit prompted the driver to correct the problem by introducing a slight 'nudge' movement at the steering wheel, not a message that many S4 drivers were interested in receiving. Unchecking the DSR box through VCDS diagnostic software fixed it for some cars but different steering issues on other cars have required the entire steering rack to be replaced.
The steering was somewhat improved on the B9, but tangible improvements to B8 turn-in and steering feel can be made by changing some of the stock chassis componentry. The so called 'alu kreuz' stabiliser is a well-rated fitment among American S4 drivers, but it doesn't fit RHD cars. The CR-15 strut tower brace that's imported into the UK from the USA by people like Brotek does work however, as do new diff mounts from the likes of Forge Motorsport. Engine mounts did have an unfortunate habit of breaking at anything over 50,000 miles.
Prior to the B8, braking in fast Audis had always felt over-assisted. This was more or less resolved in the B8 S4 which had big discs all round (vented at the front), but pedal feel still wasn't that great and a degree of squealing was reported by owners. Again, this seemed to be worse in cold weather.
In the unlikely event of you having to pick a good car in which to have an accident in 2009, an A4 derivative would have been an excellent choice. It scored five Euro NCAP stars for adult occupant protection.
Rust on the front arches under can show itself on early cars, not so much on the 8.5s. As mentioned earlier, this facelift brought a new front end look with Audi's new trapezoidal grille and wavy bottom edge headlights which could now be ordered in 'Xenon plus' spec.
Sunroof deflectors can generate a nasty noise if you're bowling along with the windows down. Updated deflectors were made available by Audi but we don't think that was a recall thing. Some owners of Advanced Key cars had trouble with door handle touch sensors caused by water ingress. This wasn't restricted to B8 S4s either: Q7s suffered from it too. The sensors and/or wiring for the headlight levelling was subject to damage, and window regulators can go west.
The bankvault build quality for which Audi became something of a byword was well in evidence in the B8 S4's cabin. You could almost hear the theme music from Terminator as you got in.
You needed that too when you'd just laid out around £40,000 for your new S4 in 2009 because the cabin ambience wasn't a good deal more special than that of a regular A4, and especially of an S line A4. It was always going to be tough compressing the S4 into a narrow marketing space that wouldn't impinge on the RS halo models. Audi swerved around this potentially thorny issue to some extent by offering Black Edition packs. As you'd expect from the name, these came with quite a lot of shiny black trim, but they also gave you a good dollop of useful stuff for £1,250, like a B&O sound system with DAB radio, a parking camera, multifunction steering wheel, 19in alloys and automatic lights and wipers.
Rear seat S4 passengers felt a bit compressed too. Although headroom wasn't a problem for most, longitudinal space was never a USP of the A4 saloon or the Avant, and occupants of the new S4 were no better off. In fact they were slightly worse off because the S4's big (and very comfortable) sports front seats cut down on the already scanty rear legroom. The saloon offered just 480 litres of boot space, which was about the same as a 3 Series or C-Class, so you needed to pack carefully for a long family holiday.
One negative aspect of regular A4s that wasn't an issue with the S4's two-pedal plus squared-off wheel cockpit was the manual A4's slightly skew-whiffed driving position. The early cars' old-school MMI controls and relatively titchy satnav screens did underline the age of the overall cabin design. These were upgraded in the 2012 facelift. Early ('09-'10) HDD satnavs were buggy. This would be fixed at the dealer but only if you were able to describe the symptoms accurately.
If this is your first Audi don't let the brand fool you into not checking that everything works – doors, bonnet, windows, the operation of the radio and mirrors etc etc. It's only a car at the end of the day.
Engaging might not be the first word that springs to mind after driving a B8 S4 for the first time – but fast, capable, strong and safe are all perfectly valid descriptors.
Although the S4's clawing traction made it nearly as fast in real-world acceleration as a BMW M3, the Audi's image wasn't as overtly sporting as the M car's. Its more natural BMW competitor in the eyes of potential buyers was probably the 335i. In that comparison the S4 had a strong badge appeal. Looking beyond the teething troubles of cars built in the first couple of years and assuming good maintenance it had potentially at least as good a reliability record.
This June 2015 saloon is one of the last supercharged B8 S4s. There's no description in the ad, but it looks sharp in the pics and both the mileage and price are low at 16,000 and £20,465. Worth a phone call you'd think.
Mapped cars shouldn't be shunned as long as you can see paperwork (receipts and dyno graphs) from a reputable outfit to back it up. The money that the previous owner will have laid out on tuning will far outweigh the uplift in the car's value so it's a cheap way of getting a whole lot more performance. Here's a perfect example, a 2012 Avant manual with several grands' worth of good-name stage 2 tuning kit taking it up to 457hp. Yours for under £15k.
This 2017 30,000-miler looks like a Black Edition car with the B&O sound system, parking camera and a load more, for £25,495. If you're feeling brave, why not dip into this 2010 154,000-mile stage 1 Avant with full history and all the important servicing and replacement parts, at £9,250.
Search for an Audi S4 here
Source: Read Full Article