Title:- Pushing the Envelope
With nearly 400bhp and a chassis that’s been honed to perfection, this Z4M Roadster is an awesome performance machine that truly delivers.
It’s fair to say that the Z4 was never quite as good as it could have been. The flame-surfaced styling divvied opinion and meant that it wasn’t as instantly appealing as the rather more easy-on-the-eye Z3; the electric power steering numbed the driving experience and caused the car to feel somewhat less scalpel sharp and the interior felt downright cheap in places. It sold well, naturally, but it didn’t really live up to its true potential until the arrival of the Z4M in 2006, which really allowed the Roadster to let its hear down. The resulting car was quite the little hooligan and more than exciting enough to allow you to forgive the Z4’s flaws. However, as well as the Z4M turned out, it wasn’t good enough for everyone….
This lush Z4M belongs to ….. and it’s fair to say he has thrown money at it, but judging by his cheery disposition, the resulting car was worth every penny. The owner came to Z4 ownership following a E46 M3 convertible and a Honda S2000 before that – he’s clearly a fan of rag-tops. “When it was time to replace the M3, I didn’t want a CSL, like most would have gone for. I wanted something quick rare and a convertible,” he explains which made the Z4M the perfect choice. “My first modification was a carbon air-box for that CSL sound and then I got the tuning bug.” As it turned out, one simple performance modification upgrade led to three years worth of extensive modifications that have taken this Z4M as far as it’s possible to go…
Once the tuning bug had bitten, the owner found himself piling on the performance upgrades, as he recalls: “I wanted 400bhp, but that’s not really possible without forced induction and without affecting the car’s drivability.” Raise that red sliver of bonnet and you’ve greeted by the carbon expanse of the air box, which dominates the engine bay – it’s a beautiful thing and its looks alone are almost worth the entry fee, the intoxicating induction howl and subsequent increase in performance merely welcome side effects. The engine has been subject to a lot of attention in order to extract as much power as possible and all the hard work has clearly paid off. Trying to squeeze yet more power out of an already highly-strung naturally aspirated engine is no easy task so you really need to hunt for each and every additional pony in every nook and cranny of the engine. The Z4M has been treated to an Alpha N-based customer live map, E46 M3 CSL Camshafts, Evosport power pulleys, larger throttle bodies along with a Supersprint stepped exhaust manifold, with this being the first RHD Z4M fitted with this manifold, and an Eisenmann exhaust. “The car was decatted for a period,” says the owner, “but it runs better with a cat in place so I had 100-cell item fitted.”
In addition to these performance upgrades, CA has fitted a number of supporting mods, namely Okada Plasma ignition coils, an oil diverter valve for increased oil cooling and an enlarged PWR radiator. The list of modifications is extensive and impressive but it does present the owner with a problem. “We’ve pretty much reached the limit of what can be done to the engine short of forced induction – I’m thinking of getting a ported, five-angle big valve race head and lightweight pistons and con rods are also an option; with these additional modifications I’d definitely hit over 400bhp”
UPDATE: Actual went for the ported, five-angle big valve race head, Schrick Camshafts Stage 2 and uprated retainers. Needs to be re-mapped now, but have noticed that the induction noise is significantly louder after 5000 revs!
While the performance upgrades are impressive, what makes this Z4M special is the fact that the chassis has received even more attention than the engine. This might come as a surprise when you learn that the owner has never actually tracked his Z4 but as it’s a weekend car it makes perfect sense that it should be set up exactly how he likes so that when he does drive it he absolutely loves every minute of it. There’s very little, if any of the standard suspension components left and the springs and dampers have been replaced with custom-made, adjustable Nitron NTR+ Coilovers, but these are just the tip of the suspension iceberg. The car has also been fitted with Ground Control anit-roll bars, a Wiechers Racing Line front strut brace, Rogue Engineering and Powerflex bushes, Rogue rear shock mounts and Simpsons Motorsport Geometry settings. The Z4M has also been treated to Stoptech brake disks, Goodridge brake hoses, Axxis ULT brake pads and RBF 600r brake fluid along with a Rogue Engineering short-shift kit and Rogue transition mounts. The owner had a 3.91 diff fitted – “before it was good but when you were driving along in a higher gear the engine was out of the power band. Now it’s always in the power, no matter which gear you’ve in” he laughs.
The owner has also paid attention to the cars styling and while the Z4M was always a mean looking hand grenade of a car, this one looks even tougher and rather more exotic than the standard machine. At the front of the car are a pair of Carbon corner splitters which are matched by a pair of carbon canards just ahead of the rear arches that provide additional down-force – there will undoubtedly divide opinion but I think they look smart and are something a bit different. My favourite part, though, is undoubtedly the AC Schnitzer Carbon fibre rear diffuser, which I think looks nothing short of spectacular. The black carbon contrast beautifully against the vibrant imola red paintwork and it looks like something that belongs on a Ferrari, giving this particular Z4M one of the most attractive rear ends I’ve seen in some time.
With the photography taken care of I’m keen to have a go in the driving seat, and the owner is more than happy to let me try out the fruits of his labour – I like this man. The Z4’s cabin is a cosy and a really nice place to be and it feels like a proper little muscle car; you feel like you’ve wearing the car and it really wraps itself around you. As the straight-six catches it instantly puts a smile on your face – it sounds fantastic piped through that Eisenman exhaust, with a meaty burble throbbing away behind your head at idle. Within mere metres it’s clear that this Z4 is a decidedly different proposition to the regular M incarnation, and it just keeps getting better. The driving experience is electrifying – the whole car feels alive and responds instantly to even the slightest of inputs. The chassis revisions have removed every last ounce of slack from the Z4M and the result is a razor-sharp instrument which will dissect and dispatch whatever road you feed it. From start to finish, the experience is one of noise and energy – a frenetic rush that gives you Goosebumps and leaves you buzzing and wide-eyed. At full throttle the induction noise is something else, an incredible blaring bark that batters you from all directions with the roof down, and as this wave of noise passes over you it mingles and mixes with the crescendo of howling straight-sex exhaust noise that is being spread across the road behind you from those quad pipes. This Z4 is fast, every bit fast as you would expect, and feels like it has 380 very healthy horses under the bonnet. But most importantly the quest for power hasn’t left drivability by the wayside. While the S54 was never about torque, this car has more of it than the standard engine and that means it’s got plenty to be getting on with – combined with the 3.91 LSD it pulls hard in every gear, no matter how many revs are showing, and it never feels like it’s out of the power band it accelerates hard in every gear and pulls all the way to the redline, the power just building and building. It really feels ferocious and the drive out of corners its stupendous. Ah yes, corners – where this car really comes alive. The amount grip that this Z4 generates is incredible and it seems like no matter how hard you push, it refuses to come unstuck. The steering is razor sharp and the car responds instantly, the front end biting hard and there’s no body roll whatsoever – the Z4 corners hard and fast and flat and the G-force it puts through your body is incredible. It feels fantastic really digging into the corners and it just grips and grips – you’d need some serious minerals lurking in your boxers to see just how hard you could push this car before it bit you. It’s wonderfully fluid through the sweeping cut through, changing direction in an instant and it feels like it has no inertia. The brakes are superb too, the modifications giving them a little more bit, a little more power and helping them to stay fade free just a little bit longer, which is particularly useful on a track like Bruntingthorpe. I give them a good work out and not once do they complain, only registering their enjoyment with some vocal ticking once I’ve returned the Z4M back to its owner, and out on the road they’d comfortably deal with whatever you might choose to throw at them. You can go into a corner hard on the brakes and marvel as it digs in and just grips all the way through, and then you can get on the power early because there’s immense traction at your disposal and just revel in the awesome delivery and immense soundtrack. It really doesn’t get much better than this. What an absolutely belting car.
The owner is thinking to the future – beyond the head work and pistons there’s not much left to do and while supercharging is an option he’s not keen because it would mean losing the induction noise from that wonderful air box – I can’t say I blame him. “A 911 GT3 would be nice but they’re too expensive,” he muses “and I’ve tried the E9x M3 but it felt a bit soft after this – I’d still like one though! I’d still keep this even if I bought something else – the amount I’ve spent means I have to!” That’s no hardship, mind – this Z4M is an incredibly accomplished package that delivers on all fronts. It looks great, it’s got power aplenty, fantastic breaks and the handling is magical. It really is as good as it gets. When modifying cars, it’s easy to get things wrong, but when it’s done right and it all comes together, the end result can blow you away.
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