Buying Guide: the sublime BMW Z4 3.0Si Coupé E86

 

Buying Guide This month it’s the brilliant Noughties Coupé, the Z4 3.0Si.


BMW said it’d never make one when it launched the E85 Z4 Roadster back in 2002 but at the Frankfurt motorshow in 2005 there it was, a ‘Concept’ Z4 Coupé. And going by the fact that this concept already had front and rear towing eye covers in its sculpted bumpers it was pretty much guaranteed that it would see production.

It arrived in showrooms in the UK in August 2006 and was available in two guises; the fire-breathing Z4 M Coupé and the slightly less frantic 3.0Si, and it’s that latter model we’ll be looking at here. While the Mpowered version was the poster boy of the range it could be argued that the 3.0Si was the better allround package, providing a better ride, excellent economy given the performance on tap and enhanced everyday usability over the M car. And today it’s a fair chunk of change less than the Z4 M to buy and run.

The 3.0Si was based on the face-lifted Roadster and used the N52 all-alloy straight-six that developed a healthy 265hp and 232lb ft of torque – good enough for a 0-62mph time of just 5.7 seconds in six-speed manual form (the six-speed auto was 0.3 seconds slower), yet it had a combined economy figure of 31.7mpg. When it went on sale the 3.0Si Coupé was listed at £31,400 for the SE version and £32,925 for the Sport model. BMW expected about 80 percent of buyers would opt for the Sport model.

BMW repeatedly mentioned the phrase ‘Pocket GT’ in its press material of the time and head of BMW design, Adrian van Hooydonk, reckoned that: “The Z4 Coupé should be considered as a fully-fledged GT car that has been shrink-wrapped around two people.” It was indeed quite snug in the Z4’s cockpit, although there was plenty of leg and headroom for taller drivers, unlike its Z3 Coupé predecessor, but interior storage space was pretty tight and door pockets could accommodate an iPhone but not much else. Luggage capacity wasn’t massive either at 340-litres but if you packed with soft bags it was generally commodious enough for most people.

You soon forgot about the tightish accommodation once on the move though as the Z4 was a great drive. The superb N52 ‘six dominated proceedings with a great spread of torque and a wonderfully linear power curve that meant it was happy to rev and rev. While a 5.7-second 0-62mph time might not sound stellar these days, nigh-on ten years ago it wasn’t half bad for a £30k coupé and the slick six-speed manual allowed you to extract the best from the car. Perhaps the auto suited the car’s character slightly less well, but it was a decent box and came with steering wheel mounted-paddles to further engage the driver. We first drove the car on its UK launch up in Scotland and on deserted Highland roads it was an absolute blast. The only slight fly in the ointment could be the electric power steering setup (one of BMW’s first attempts) which wasn’t as feelsome as a full hydraulic setup and when the road surface deteriorated those run-flat tyres didn’t smooth things out quite as well as standard tyres would have.

When the Z4 Coupé hit the road in the UK it could have been ordered in Alpine white, Jet black and Bright red or as a no-cost option the metallic shades of Titanium silver, Black sapphire, Montego blue, Silver grey, Deep green and Monaco blue could be spec’d. Given it was a no-cost option most owners went for the metallic. The Individual colours Pheonix yellow, Midnight blue and Ruby black were also available while inside owners were treated to Oregon leather seats in either Black, Dream red, Beige or Pearl grey. Extended Individual leather was also offered as an option at a hefty £2200.

SE models came as standard with 17-inch alloys, DSC+, a rain sensor, run-flat tyres, metallic paint and auto air-con but that was about it. Sports added the expected 18-inch M Sport rims, an anthracite headlining, brushed aluminium interior trim, M Sport seats, M Sports suspension and an M three-spoke steering wheel. You could have bumped the list price up quite significantly if you’d gone wild with the options list with the auto ‘box costing £1525, xenon headlights at £415, £1495 for Professional navigation and an eye-watering £710 for TV on that folding nav screen. Even cruise control and rear PDC were options. Those wanting Bluetooth hand’s free functionality should note that this was also an option at £390.

Don’t let that put you off though as the Z4 3.0Si Coupé is a cracking drive irrespective of which options it has fitted, and many first owners ticked quite a few boxes to ensure their Pocket GTs were to their liking. It was expected that the Z4 Coupé was going to be a brisk seller, but it didn’t capture the imagination as much as the Z4 Roadster and in total just 2655 were sold in the UK compared to nearly 8500 Z4 Roadsters in the same timeframe. It ended production in 2008 and was replaced by the all-new E89 Z4 which aimed to provide the best of both worlds with its folding metal hard-top. It was a good car, but less exciting to drive than its Coupé predecessor.


Buying one

Despite selling in relatively small numbers there are still plenty of 3.0Si Coupés to choose from with early, very miley machines starting at about £6000-£7000 but by the time you get to £8500 you should be looking at a car with sub-100k miles and some history.

By the time you get to £10,500 you should be able to bag a Sport with around 50-60k miles on the clock and prices go up to around £15k for the very best late model examples with low miles. You might even still find one at an official BMW dealer – there were three up for grabs when we were looking, two at £12k and one with just 14,000 miles from new for a hefty £17,500.

However, with the Z4 having a pretty decent reliability record we wouldn’t necessarily go out looking for one from a dealer as it’s perhaps less vital to have the warranty on this model than some other BMWs.


Engine

The N52 unit as fitted to the 3.0Si is a real gem, a 265hp straight-six that is pretty much perfect. Whilst the earlier pre-face-lift Z4 Roadster used the 231hp M54 from the late Z3 and the E46 330i range, the all-new N52 has that nice wodge of extra grunt and ‘zing’. Unencumbered by the later direct injection setup and its injector noise and carbon build-up problems, the N52 3.0-litre is probably the zenith of BMW straight-sixes.

What goes wrong? Not a lot. The N52 does, however, have the potential for an expensive problem where the steel oil sealing rings at the front of the cams can wear a groove into the alloy cam carrier. These sealing rings are to prevent excess oil escaping from the cam bearings when it should be activating the Vanos units and the result is an engine light coming on because the Vanos isn’t operating correctly. The lower the mileage the car has done, the lesser the chances of this happening but we’ve seen 150,000 mile cars that still run fine. What makes it doubly complex is that the inlet bearing ledge is integral with the head so if the inlet bearing ledge is worn, you need either a new head assembly at a mere £4000 or a used engine that may be on the verge of a similar problem. Given how common the N52 is (E90 range, E60 etc) there needs to be a clever cure for this – I’ve heard of the upper ledge being removed, alloy welded and re-machined to improve matters, leaving just the lower part worn – not ideal. The exhaust bearing ledge is replaceable and costs £365 plus four to five hours labour.

Of more concern is a light chattering/knocking noise from the engine. This often sounds like it could be a piston issue but is in fact wear in the cam carriers allowing the tappets to ‘rock’ slightly. Thicker oil might mask the problem to sell the car so don’t fall for that one – a good N52 will idle very quietly. Oil changes are critical, so ignore the service system and change the oil every year or 8000 miles with a fully synthetic. The N52 is a great engine, but the older M54 used in the Roadster is probably more robust in old age. The N52 also has an electric coolant pump and whilst failure is quite rare, it does happen.

Avoid used ones because once removed and allowed to dry out, they can leak badly on re-use. From BMW a new pump is just over £500 but you can buy the same Pierburg pump from ECP for £380 all-in – that’s still a long way from the £35 the good old belt driven pump costs!

Unlike the N42/46 four-pot engine, the Valvetronic actuator rarely fails and if it does, a new one is less than £250 plus fitting. Some BMW parts prices are surprising – some are pretty extreme but others are very fair. For example, a new radiator from BMW is a reasonable £275 all-in and given the experiences many have had with aftermarket rads, we would strongly recommend you only use a BMW branded item. Nissens come a fairly close second but there are too many radiators with well-known names that should be trustworthy that are absolute junk – a radiator should last eight to ten years so it’s a small investment for peace of mind.


Steering and suspension

In terms of the suspension, the Z4 inherited the E46-style Z axle from the E46 and really, it’s no bother at all. The cracking around the rear subframe mounts as per E46 is unheard of – I’ve never seen or heard of it, and neither has anyone else I’ve spoken to. So good is this rear suspension, it was used in slightly modified form in the latest Z4 – not bad for a design launched in 1989.

The front end is mostly E46 as well – the crossmember and the wishbones are the same as are the front hubs and whilst the alloy wishbones cannot have individual ball joints replaced, you can get a complete new arm for around £130 a side from Lemforder.

Common issues both front and rear will include worn rear trailing arm outer bushes as well as tired front wishbone rear bushes, but both are cheap to replace and not impossible for a good DIY mechanic.

Nothing’s perfect though, and the fly in the ointment is the electric PAS system. Unlike the later E90 that had a motor on the rack itself, the Z4 range (except for the Z4M) had an electric column operating on a steering rack that looks like it came from a 1600 Sierra – it’s odd looking at a basic non-assisted rack these days. The electric column motor works well, but pray that it doesn’t fail because a new one is a staggering £2600 before fitting and coding.

Used columns require extreme caution because it needs to be removed carefully in the locked position. Like the N52 cam bearing problem, there is a market here for a fluid PAS conversion using an E46 rack (£50 tops), PAS pump from an E60, some custom pipework and a modified column as well as a remap to restore lost throttle response – the Sport button is activated by the electric steering motor but all that does is alter the speed at which the throttle reaches wide open status so it’s not essential.


Body

Like all of the recent generation BMWs, the Z4 doesn’t really rust even though the oldest ones are now 13 years old – think back to when an MGB or TR7 was little more than compost at that age and be thankful that the only rust area on the Z4 Coupé is the inner tailgate seams. It’s only really visible with the rear hatch open, but inspect the seams anyway and just look around the whole car for any signs of repaired damage, iffy shut lines and so on. But as it should be on a car that’s only around ten years old, the car should still be straight and clean – make sure the central locking works properly. If not, it could be a GM module, a dying key battery or a faulty lock. None of these are particularly pricey to fix however. Like the Roadster, the Coupé doors tend to slam shut with a slightly tinny clang.


Transmission

The Getrag GS6 six-speed manual ‘box is a tough old bird and rarely gives aggro. Change the oil every now and then and it’ll just last forever. Similarly the dual mass flywheel which, on a smooth straight-six petrol, has an easy life. Clutch kits are decent value at under £200 all in from various aftermarket sources and that’s for a proper LuK kit – why pay more?

Some Si cars had the six-speed ZF auto, another fine transmission. Maintenance is the key and whilst you can just leave it alone (as most do), some say an oil and filter change at 50 to 100 thousand miles is a good plan.

Certainly, an oil leak from the sump or the electrical connector plug needs fixing and again we’ll say: only use proper parts from BMW. Yes, they’re made by ZF but the oil pan service kit is only £167 and it’s guaranteed to be proper quality – the slightly cheaper kits made by companies with Teutonic sounding names just aren’t as good and many will warp and leak rendering the whole thing a waste of energy.

The six-speed auto rarely goes wrong, and shifting problems – if not cured by a software update – are often down to a faulty solenoid or the rubber bridge seal between the valve block and transmission casing. Props and diffs are all very similar to the E46 330i and along with the driveshafts, are near enough unbreakable.


Interior

The Coupé inherited most of the Z4 Roadster’s interior including quite a wide range of leather colours including red. Air-con was standard of course but depending on year, the standard equipment was anything but generous – PDC was an option that’s really worth having whilst the professional nav that was a deal-breaker when new is perhaps not that vital nowadays. Other standard equipment included a single slot CD player, black headlining and a cigarette lighter (the ‘smokers package’!) and not a lot else but, really, what more do you need? Put any paucity in spec to your advantage with a cheaper outlay if you’re keeping it a few years. Electric seats are quite common so make sure they all work as they should. A worn seat bolster can be replaced by a decent trimmer for 100 quid or less.


Electronics

We will include the headlights here as we have a choice of standard Halogen and optional Xenons. For anyone who likes to see where they are going on a dark, wet night the Xenons are the only choice, but if you have a problem, you’ll need a booster pack for your wallet and a paramedic when they tell you how much a new headlight is – £885 plus fitting. The lights themselves rarely go wrong but a booster pack for the bulbs might, and they’re just the right side of £400, each. If the car is a rarely used toy, you’ll be glad to know a standard light is £380 but in our view, the Xenons are worth the risk. We mentioned the GM (general module) earlier that controls the locking, windows and wipers but the wiper linkage itself can break and whilst they can be repaired with skilled welding, a good used linkage might be a better option as they’re £370 new. The electric windows use an E46-style cable and motor system and whilst it’s not that common for the regulators to fail, they’re just under £200 a side with no aftermarket option. The rest of the car has what are basically E46-style electrics and of course there is no troublesome electric hood motor – all-in-all then, the Z4 Coupé’s electrics don’t really present any significant problems.


Wheels, tyres and brakes

Standard rims on the SE were 17-inch alloys (Star spoke Style 200) while Sport models received 18- inch items with the M Double spoke Style 135 MV2 being the standard fitment. Various 17- and 18-inch wheels were optional on the SE but the only optional wheel listed for the Sport model was the Star spoke Style 108. You’re looking at £200 for a pair of tyres – Hankook Optimo K415s are £180 a pair plus fitting, whilst Continental Sport Contacts are closer to £250.

Brakes are a surprise in terms of price. The ABS unit is predictably expensive at almost £2000 – they rarely go wrong but you just wouldn’t pay such an insane amount. So I asked my local BMW dealer parts guy to recheck the price of the drilled and vented front discs – almost laughably cheap at £109 the pair with VAT. It seems that BMW offered this disc as a BMW Performance upgrade for the Si to replace the standard vented discs – and the non-drilled ones are no longer available, replaced by the bargain priced drilled ones. In comparison, Pagid non-drilled discs are £86 a pair. That’s why BMW only want £219 to supply and fit front discs and pads.

Rusty brake pipes may just be creeping into the 2006 Z4 but a nice garaged car should still be on good clean originals. Like the X5, Z4 handbrake ratchets can occasionally strip the teeth but a new assembly is cheap enough at £135 all-in and are easy enough to fit.


Servicing costs

The Z4 doesn’t need a lot of looking after really. We would have an oil change done every year regardless of mileage or at around 8000 miles – BMW dealers ask £189 for this which isn’t bad really. Due to the low cost of the brake discs, for a dealer to change the front discs and pads is almost a bargain at £217. In fact, considering the £88 price difference it’s worth paying the extra and having new discs if in any doubt. BMW dealerships are as receptive to haggling as anywhere else, so ring around a 50-mile radius and you might be surprised – they are keen to compete with independents.


Verdict

When the Z4 Coupé arrived in 2006, everyone – myself included – thought it was going to be a monster hit. With overtones of the Triumph GT6 from some angles and the best bits of the (very pretty) E85 Z4 as well as 265hp, what wasn’t to like? But for whatever reason – probably price – it wasn’t to be and the Z4 Coupé became a showroom static exhibit.

So it’s odd how prices have firmed up and depreciation has been kind to the Coupé – you’ll need just £6500 for the earliest, 150,000 mile car and nice late model cars on 2008 registrations are 12 or 13 grand’s worth with low milers selling for up to £15,000. That overlaps the early 2009 E89 cars, but unless you really must have the electric folding metal roof, the older car is a more alluring package – the lack of an electric handbrake and the raw gutsy feel all add to an already convincing set of virtues.


TECHNICAL DATA BMW E86 Z4 3.0Si Coupé

ENGINE: BMW N52 straight-six, DOHC, 24-valve

CAPACITY: 2996cc

MAX POWER: 265hp @ 6600rpm

MAX TORQUE: 232lb ft @ 2750rpm

0-62MPH: 5.7 seconds (6.0)

STANDING KM: 25.2 seconds (25.3)

50-75MPH (FOURTH GEAR): 5.2 seconds

TOP SPEED: 155mph (155)

ECONOMY: 31.7mpg (31.4)

EMISSIONS (CO²): 213 g/km (216)

PRICE (OTR): From £31,375 (2006)


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