Audi S5 Sportback, BMW 435i Gran Coupé, Frontansicht 26 Photos Zoom

Audi S5 Sportback vs. BMW 435i Gran Coupé: Not just a pair of autobahn brawlers

With four doors and fastback styling, the Audi S5 and BMW 435i are reclaiming the coupé moniker for sturdy, practical cars. Which best achieves the balancing act of passion and practicality?

“Driveability” sounds like a fairly abstract, new-age term, with no real meaning. But more fool you if you ignore it when looking for your next car. Because driveability has two distinct yet equally important meanings; this is something that is made clear when driving either of the two cars on test here.

Before we get to the cars, let’s clear up these meanings. The first interpretation of the word is objective, how hard you’re able to drive the car, and can be quantified in km/h, G-Force and a whole host of other metrics. This side of driveability is seen when you push the car to its limits. Understood so far? Wonderful. Now on to the second interpretation. This intangible, emotional side of driveability isn’t defined by a formula of longitudinal, lateral, and negative acceleration. It is felt in your palms, the tips of your feet, and the seat of your pants. It cannot be measured or expressed as a list of numbers, and, occasionally but by no means rarely, contradicts the objective evidence of driveability!

Audi S5 Sportback - all bark no bite?

Sometimes you get into a car and think “wow - the cornering, grip, acceleration - this is a serious machine”. And then, as soon as you really start to push the envelope, you realise that all this hype really is just that – there’s nothing behind it. Audi’s S models have traditionally been guilty of following this trend. Some are even of the opinion that Audi started off the whole trend. But it doesn’t matter; nobody is boycotting the S models, and if they are, it isn’t noticeable. The S6, S7 and S8 are masters of the driveability-illusion, and even the S3 isn’t as performance focused as Audi would have you believe. The same can be said of the S1 But there is one exception – the S5. This doesn’t make a big song and dance about its performance, especially in the power delivery.

The 3 litre compressor engine is generally well developed: immediate, enduring, and will certainly prove hard to beat for the BMW 435i. However this raw performance is hidden away. In plain English: Although the S5 impresses in our head to head with the 435i – with launch control and four-wheel drive it takes off like a rocket, accelerates as if by itself, and changes gear with no discernable loss in power – in everyday usage it seems sluggish, pained even. The question is of course: Why?

Dissonance between rhythm and thrust in the Audi V6

Two theories: One is based on the Audi’s long gear ratios, which aren’t the most conducive to sudden sprints – this requires downshifting or advanced conditioning. Theory two is based on the sound the Audi makes. This is generated artificially, and is pumped into the cabin by a symposer. Whether that’s a good thing is a discussion for another time.

The issue here is that there is a dissonance between the engine noise and its thrust. The roar created by the symposer doesn’t match with the occasionally less than ambitious power development. In short: The two just don’t fit together – it’s like having techno backing music to a love ballad, and this alters your perception. In this case, to the detriment of the Audi.

BMW 435i Gran Coupé convinces with its smooth six-cylinder

The BMW 435i behaves in the opposite manner. It’s the objectively slower car of the two. Not by any rate slow, but still not as quick as it feels when driving it. But as we have said before, that’s no cause for concern; it’s nothing out of the ordinary. And this is perhaps what the consumer wants, when searching for a car with the coupé characteristics, but deciding against a coupé. The turbocharged three litre engine is silky smooth and effortless. And the sound... An ever-perfect harmony of drones and rattles. It has character and charm; some say that the heart of motoring lives on behind the kidney shaped grille of a BMW. Even if that is largely correct, the 435i must also thank its transmission for its performance.

BMW is currently on several uncharted paths: they’ve started building people carriers, three cylinder engines, front wheel drive cars – not BMW at all. But the 435i’s combination of straight six and sporty automatic transmission make it a true masterpiece. Relaxed yet playful, the two dance across any hurdle, complementing each other perfectly, and whipping each other into a frenzy when you’re riding the red line. The only real problem is the body in which it all sits. As is the case with the S5 Sportback, the Gran Coupé is a rolling compromise of space, sportiness, status and image. And if you’re buying for image, then you’re clearly looking for a lazy one; they’re larger and heavier than the respective Coupé versions, yet tighter than the estate versions of the 3 Series or A4. Put harshly, they unite the disadvantages of both worlds.

No high-performance model of the BMW 435i planned

Still, these fastback models have their upsides, and not just stylistically. Audi crams its top of the range 333 BHP engine into the S model, whereas the 306 BHP BMW can be upgraded with certain extras to approach the same sort of performance: an M package, 19 inch rims, you could even have four wheel drive. However a full M Performance package à la M235i isn’t planned. Indeed, you can get pretty much everything individually as an extra – both the carbon fibre components and the rear axle locking mechanism fitted to the car pictured cost almost 3000€ – labour on top, of course.

Audi’s rear axle lock, or “Sport Differential”, is also only available as an extra, costing you an additional 900€. In contrast to the BMW offering, it is electronically controlled, and also uses active torque vectoring, all this however under far more testing conditions. Let’s put it like this: The BMW 435i Gran Coupé is more athletic from head to toe – it’s a good 120 kg lighter than the Audi S5 Sportback, which has always-activated four-wheel drive. Therefore, the BMW doesn’t have to compensate for much; minor tweaks are all that is needed. And that is what it offers: both traction and cornering are that little bit better with the rear axle lock than on the standard car. In short: it’s a nice addition for the driveability, both the objective and subjective varieties.

Audi S5 Sportback demonstrates technical prowess in Hockenheim

On the other hand, the Audi needs this addition in order to claim that it has any kind of driveability! We have never been given an Audi S5 Sportback to test that wasn’t fitted with the Sport Differential. And as soon as you’ve finished the first couple of bends, it is very clear why that is. Through the redistribution of torque to the loaded rear wheel, a turning force towards the apex of the curve is generated. This allegedly eliminates understeer. Not entirely however, as we found: in very tight corners, the Audi S5 Sportback still tries to force itself over the front axle, but the Sport Differential makes a clear difference. It is so keen that you’d have to calm it down by putting it in comfort mode to even contemplate a slalom course.

The Audi really showed the merit of its technology on the Hockenheim racetrack though. It’s deliberate and precise in fast corners, and through wide-angled corners it bites and toils to keep your momentum up. Most importantly: it is here on the track – where the motor runs at higher revs and never gets the chance to get bogged down in the higher gears – that both sides of the coin of driveability are in harmony. In other words: the S5 drives energetically, and feels it too.

BMW 435i Gran Coupé lacks that final something

The BMW 435i finished half a second behind in our race against the Audi – a result perhaps not everyone would have expected. “Of course that’sgoing to happen” the BMW hardcore will chime in “the test car lacked four-wheel drive!” Fair enough, but it’s not as simple as that. For one, the BMW commands a significant weight advantage due to this. It has also been proven time and time again in tests, that the xDrive models perform very similarly to BMW’s rear-wheel drive offerings.

The reason for BMW’s loss in this race isn’t lacking hardware, rather in how the car performs. And the closer you take this car to the limit, the wider the gap between performance and how it feels. In simple terms: despite all the M extras, the BMW 435i Gran Coupé remains one of those 95% models, of which BMW produces so many, ignoring the thoroughbred M models.

Having said that, the BMW corners directly, the steering wheel behaves well in your hands, and the turbo allows for a very precise application of power. The BMW just doesn’t offer as much resistance to the lateral forces at work as the S5 does. The chassis tilts too much, and from a certain point the chassis pretty much loses lateral control, primarily on the front axle. And as we have said time and time again about the use of mixed tyres, they were useful back when BMWs were untameable rear-wheel driven beasts, when the rear was so light that nothing was off the table when it came to giving it grip. They’re utterly superfluous – indeed counter-productive – on a finely tuned 1.7 tonne motorway cruiser. Of course, we are talking in terms of objective driveability – getting the maximum out of the car.

Author

Photo

Rossen Gargolov

Date

18 October 2015
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