Great Review of the 997 C4.2 from Drivers Republic
Aug 5, 2008 | 12:36 PM
#1
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From: Zoo York
Great Review of the 997 C4.2 from Drivers Republic Porsche spends a great deal of time and money developing the four-wheel drive version of its Carrera. Its brief is simple: in the dry it should mimic the behaviour of the standard Carrera and in the wet bring added security and traction.
But the simple brief has a not-so-simple solution, involving the electronically controlled PTM (Porsche Traction Management) system from the Turbo and a standard-fit rear limited-slip differential.
The control unit that determines how much power to distribute between front and rear axles is a work of genius - not only measuring wheel speeds and lateral forces but also taking account of the steering angle before shuffling the torque. The aim is to prevent under- or oversteer before they occur, but if the car is sliding and you're already applying corrective lock the C4 will work with your reactions to bring things under control more smoothly and more quickly. And all this in no more than 100-milliseconds.
Despite such technological brilliance it’s a sad fact of life for Porsche’s chassis and transmission engineers that many customers are almost certainly going to choose the C4 on looks alone. The old school reflector strip across the back split opinion (I love it, many didn't) - but the wide body from the Turbo and GT3RS is a universal hit, accentuating the 997's curves without looking OTT. If you love the look then the circa-£4000 premium Porsche wants for the C4 over the C2 is money well spent. Whether its multi-plate clutch in the front axle, PTM system and rear limited-slip diff have a similarly transforming effect on the dynamics should be revealed on quiet roads near Berlin and a Michelin test facility located on an ex-Cold War Russian airbase nearby.
Unfortunately the road driving on offer is restricted to roads that are either straight and very smooth or so badly surfaced that driving quickly is out of the question. On the few sequences of corners we do find the C4 feels agile and grippy, with just a shade more understeer than you might find in the standard Carrera. The wider rear track and huge 295-section (305-section for the C4S) tyres give the rear axle enormous grip so its no surprise that the front pushes wide first when you start dipping into the 3.6-litre, 340bhp (345PS) flat-six. I should mention that the new direct-injection unit feels strong and punchy low down and revs with a zip to the limiter. In fact such is the acceleration, the glorious noise and the sheer enjoyment you get from this engine that you can't help asking yourself if you'd bother with the 380bhp 3.8-litre engine in the 'S' version. Hooked-up to the 7-speed PDK 'box, as it was on our test car, the C4 feels plenty fast enough.
There are other subtle differences too, chief among them a steering rack that is just a shade heavier, making the C4 feel a little less keen to change direction. But on unfamiliar roads - and even though I'd literally driven to the airport in a C2S - the C4 feels very, very close to its rear-drive sibling. So close you might begin to wonder why you'd bother...
PLUS: Four-wheel drive system works superbly in low-grip situations and there's little penalty in terms of weight or on-limit dynamics. Usual 997 strengths - performance, brakes, grip and balance - are intact
MINUS: A trace more understeer than the C2 or C2S and a bit of agility is lost. Counter-intuitive PDK shifters are awkward to use
But the simple brief has a not-so-simple solution, involving the electronically controlled PTM (Porsche Traction Management) system from the Turbo and a standard-fit rear limited-slip differential.
The control unit that determines how much power to distribute between front and rear axles is a work of genius - not only measuring wheel speeds and lateral forces but also taking account of the steering angle before shuffling the torque. The aim is to prevent under- or oversteer before they occur, but if the car is sliding and you're already applying corrective lock the C4 will work with your reactions to bring things under control more smoothly and more quickly. And all this in no more than 100-milliseconds.
Despite such technological brilliance it’s a sad fact of life for Porsche’s chassis and transmission engineers that many customers are almost certainly going to choose the C4 on looks alone. The old school reflector strip across the back split opinion (I love it, many didn't) - but the wide body from the Turbo and GT3RS is a universal hit, accentuating the 997's curves without looking OTT. If you love the look then the circa-£4000 premium Porsche wants for the C4 over the C2 is money well spent. Whether its multi-plate clutch in the front axle, PTM system and rear limited-slip diff have a similarly transforming effect on the dynamics should be revealed on quiet roads near Berlin and a Michelin test facility located on an ex-Cold War Russian airbase nearby.
Unfortunately the road driving on offer is restricted to roads that are either straight and very smooth or so badly surfaced that driving quickly is out of the question. On the few sequences of corners we do find the C4 feels agile and grippy, with just a shade more understeer than you might find in the standard Carrera. The wider rear track and huge 295-section (305-section for the C4S) tyres give the rear axle enormous grip so its no surprise that the front pushes wide first when you start dipping into the 3.6-litre, 340bhp (345PS) flat-six. I should mention that the new direct-injection unit feels strong and punchy low down and revs with a zip to the limiter. In fact such is the acceleration, the glorious noise and the sheer enjoyment you get from this engine that you can't help asking yourself if you'd bother with the 380bhp 3.8-litre engine in the 'S' version. Hooked-up to the 7-speed PDK 'box, as it was on our test car, the C4 feels plenty fast enough.
There are other subtle differences too, chief among them a steering rack that is just a shade heavier, making the C4 feel a little less keen to change direction. But on unfamiliar roads - and even though I'd literally driven to the airport in a C2S - the C4 feels very, very close to its rear-drive sibling. So close you might begin to wonder why you'd bother...
PLUS: Four-wheel drive system works superbly in low-grip situations and there's little penalty in terms of weight or on-limit dynamics. Usual 997 strengths - performance, brakes, grip and balance - are intact
MINUS: A trace more understeer than the C2 or C2S and a bit of agility is lost. Counter-intuitive PDK shifters are awkward to use
Aug 5, 2008 | 12:37 PM
#2
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Joined: Jan 2008
Posts: 31,554
From: Zoo York
the rest of the review...
Fortunately we have a dry handling track, simulated wet-grip circuit on polished tarmac and a slalom course doused with hundreds of gallons of water that replicates a snowy surface on which to explore the C4’s limits. The simulated wet surface isn't actually that much more slippery than dry tarmac, however it does reveal just how good the C4's traction is. Out of tight hairpins the car never needs to use its PSM traction and stability control systems, and through the quicker 3rd-gear corners there's a similar lack of drama. Which isn't to say that the C4 is just a point-and-shoot machine. Turn off the PSM and it feels very adjustable, tweaking its balance through the quicker turns depending on your throttle input and proving very keen to slip into turn-in oversteer should you have an exaggerated lift of the throttle on corner entry.
Once the tail is swinging the C4 requires less subtlety than the C2 to recover - you can jump on the power and feel the front wheels pulling you through the slide. However, it's still a rear-engined car and even though the PTM is juggling drive quickly to optimise traction you'll need to be quick with your first corrective input to prevent an ungraceful spin (to which I can testify!). It's still a 911 after all.
At track speeds the mild understeer I mentioned earlier is less evident. On the road you tend to turn-in with a good margin of error and then get on the power hard as the corner opens out, unbalancing the car as you do so. But here on the track you can fully commit to the corner so that the chassis is balanced right from the entry. Suddenly the C4 finds a more fluid, more malleable balance. In fact you can ignore much of the 911 received wisdom and brake hard right into the apex, the front tyres biting determinedly, the rear tyres just edging wide to keep things neutral. You can certainly take liberties that a C2 might not tolerate. On the proper 'outer handling' track the C4 feels superb, dealing with direction changes with total efficiency and carrying huge speed. Our test car was fitted with the optional ceramic brakes and they work brilliantly and never hint at fading. Once again the 3.6-litre engine proved almost a match for a C4S I was following, just losing a half a car length or so between gearshifts.
Speaking of gearshifts, the odd PDK shift controls mounted on the steering wheel spokes are a problem on track. The counter-intuitive push-for-upshifts, pull-for-downshifts system does become more instinctive with practice, but when you're busy on the steering wheel it's all too easy to unintentionally get an upshift mid-corner. It's frustrating and what's worse is that your contact with the steering (for so long a defining feature on any 911) is now conducted through the hard shiny plastic shifters. I'd stick with the manual and save £2338.
So the C4 is an excellent car - the four-wheel drive system works imperceptibly and any deterioration in feedback is marginal. Better still it retains its composure right up to the limit and beyond, which isn't true of the last C4 (the previous car had a slower-reacting mechanically controlled four-wheel drive system), which was a car that could get surprisingly ragged when pushed hard. In low grip situations it's superior to the C2 and only 55kgs heavier. However, whether the C4 makes sense depends largely upon where you live. In colder parts of Europe or the US it's a no-brainer, but in the UK it'll rarely prove advantageous to have the C4. And although it sacrifices little in dynamic terms it's a penalty I wouldn't want to pay a premium for.
Fortunately we have a dry handling track, simulated wet-grip circuit on polished tarmac and a slalom course doused with hundreds of gallons of water that replicates a snowy surface on which to explore the C4’s limits. The simulated wet surface isn't actually that much more slippery than dry tarmac, however it does reveal just how good the C4's traction is. Out of tight hairpins the car never needs to use its PSM traction and stability control systems, and through the quicker 3rd-gear corners there's a similar lack of drama. Which isn't to say that the C4 is just a point-and-shoot machine. Turn off the PSM and it feels very adjustable, tweaking its balance through the quicker turns depending on your throttle input and proving very keen to slip into turn-in oversteer should you have an exaggerated lift of the throttle on corner entry.
Once the tail is swinging the C4 requires less subtlety than the C2 to recover - you can jump on the power and feel the front wheels pulling you through the slide. However, it's still a rear-engined car and even though the PTM is juggling drive quickly to optimise traction you'll need to be quick with your first corrective input to prevent an ungraceful spin (to which I can testify!). It's still a 911 after all.
At track speeds the mild understeer I mentioned earlier is less evident. On the road you tend to turn-in with a good margin of error and then get on the power hard as the corner opens out, unbalancing the car as you do so. But here on the track you can fully commit to the corner so that the chassis is balanced right from the entry. Suddenly the C4 finds a more fluid, more malleable balance. In fact you can ignore much of the 911 received wisdom and brake hard right into the apex, the front tyres biting determinedly, the rear tyres just edging wide to keep things neutral. You can certainly take liberties that a C2 might not tolerate. On the proper 'outer handling' track the C4 feels superb, dealing with direction changes with total efficiency and carrying huge speed. Our test car was fitted with the optional ceramic brakes and they work brilliantly and never hint at fading. Once again the 3.6-litre engine proved almost a match for a C4S I was following, just losing a half a car length or so between gearshifts.
Speaking of gearshifts, the odd PDK shift controls mounted on the steering wheel spokes are a problem on track. The counter-intuitive push-for-upshifts, pull-for-downshifts system does become more instinctive with practice, but when you're busy on the steering wheel it's all too easy to unintentionally get an upshift mid-corner. It's frustrating and what's worse is that your contact with the steering (for so long a defining feature on any 911) is now conducted through the hard shiny plastic shifters. I'd stick with the manual and save £2338.
So the C4 is an excellent car - the four-wheel drive system works imperceptibly and any deterioration in feedback is marginal. Better still it retains its composure right up to the limit and beyond, which isn't true of the last C4 (the previous car had a slower-reacting mechanically controlled four-wheel drive system), which was a car that could get surprisingly ragged when pushed hard. In low grip situations it's superior to the C2 and only 55kgs heavier. However, whether the C4 makes sense depends largely upon where you live. In colder parts of Europe or the US it's a no-brainer, but in the UK it'll rarely prove advantageous to have the C4. And although it sacrifices little in dynamic terms it's a penalty I wouldn't want to pay a premium for.
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