BMW’s peren­ni­ally mis­un­der­stood sports car is back; new plat­form, se­ri­ous en­gine, real in­tent. Is the new Z4 a driver’s car to re­ally be­lieve in?

CAR (UK) - - NEW BMW Z4 - Words James Tay­lor

ES­TAB­LISHED ROAD­STER LORE: Porsche’s Boxster is a great driver’s car, while the Audi TT looks the part but doesn’t drive like it. And the BMW Z4? Bit of both.

At its worst, the Z4 has been a boule­vardier that pri­ori­tises pose over poise. Great en­gines, so-so chas­sis. At its best (Z4M Coupe), it’s mixed brave de­sign with proper hairy-chested driv­ing dy­nam­ics.

And now we’ve a new one, a ma­chine BMW’s adamant is an out-and-out sports car. With six-cylin­der power where Porsche only of­fers a four, could the Z4 now be the de­fin­i­tive £50k sports car?

While the Z4’s been de­vel­oped in con­junc­tion with Toy­ota’s new Supra (see page 78), there’s plenty of clear wa­ter be­tween them. The Supra will be avail­able only as a fixed­head coupe, the BMW a sun-seek­ing soft-top. Why a fab­ric roof in­stead of the pre­vi­ous E89 Z4’s fold­ing hard­top? It’s lighter, it’s faster (tak­ing around 10sec to go from rain­swept to cosy, half the time of the old fold­ing hard­top), it lets in less noise on the move and it low­ers the cen­tre of grav­ity a touch. More pro­saically, it means you also get the same lug­gage space whether the roof’s up or down, so there’s a fixed 265 litres in­stead of the old car’s 310 roof-up, 180 roof-down.

Whether the roof’s up or down, re­fine­ment is im­pres­sive for a road­ster. There’s very lit­tle flex in the Z4’s struc­ture, and that rigid­ity is as much a boon for com­fort as it is for agility, ex­tra brac­ing giv­ing the sus­pen­sion a con­sis­tent ba­sis from which to work. El­bow propped on the door’s comfy arm­rest, back soothed by the plump seats just as the pli­ant sus­pen­sion smooths the road, miles slide by eas­ily in the Z4.

And when you de­cide to up the pace a lit­tle? This Z4 is quick. There’s al­ways been at least one doozy of an en­gine in the Z4 line-up (the M3-de­rived 3.2-litre straight-six in the Mk1’s Z4M vari­ant; the 3.0 twin-turbo straight-six4

in the Mk2’s range-top­per) and the new car is no dif­fer­ent – the top M40i vari­ant still packs a straight-six. A 336bhp evo­lu­tion of the B58 en­gine seen in the M140i/M240i and 340i/440i, the unit’s twin-tur­bocharged but with its throt­tle re­sponse sharp­ened by soft­ware controlling the waste­gate. It was also bench­marked against the nat­u­rallyaspi­rated old Porsche six (God rest its soul).

Now that the Porsche is a four-cylin­der, the six gives the Z4 some­thing of a the­o­ret­i­cal USP. Match­ing its Stuttgart ri­val’s han­dling is a tougher ask, though, and BMW has en­deav­oured to give the Z4 the best start in life by putting two thirds of the en­gine be­hind the front axle for a claimed 50:50 weight dis­tri­bu­tion – the sports car holy grail – and mak­ing it both con­sid­er­ably wider in track (by nearly 100mm at the front) and shorter in wheel­base than the pre­vi­ous Z4. Kerb weight is 1535kg for the M40i, and its 19-inch wheels are wrapped in iden­ti­cal Miche­lin Pi­lot Su­per Sports to those of the BMW M3/4, right down to the size and com­pound. Sus­pen­sion is by MacPher­son strut at the front, multi-link at the rear, and the M40i gets adap­tive dampers as stan­dard, along with up­rated brakes and an elec­tron­i­cally con­trolled lock­ing diff (es­sen­tially a scaled-down ver­sion of the M5’s unit).

The way the steer­ing, dampers and diff in­ter­act is key to the Z4’s dy­nam­ics. Turn the wheel and the out­side front shock stiff­ens ac­cord­ingly, for the sharpest pos­si­ble turn-in, and the sus­pen­sion’s bal­ance front-to-rear is ma­nip­u­lated on the fly for op­ti­mum agility.

‘You can’t di­vide steer­ing, dif­fer­en­tial and dampers; they all in­ter­act,’ says driv­ing dy­nam­ics en­gi­neer Flo­rian Di­et­rich. ‘All four dampers’ com­pres­sion and re­bound rates adapt within 20 mil­lisec­onds, tak­ing into ac­count cor­ner speed, steer­ing an­gle, how fast you’ve turned the wheel, and more.’

As is the wont of mod­ern BMWs, switch­able driv­ing modes for steer­ing, dampers, gear­box and en­gine re­sponse ramp up through Com­fort, Sport and Sport +, but there’s a more marked dif­fer­ence in feel be­tween them than be­fore. In the lat­ter two, the M40i is re­ally quite tail-happy; be­gin to squeeze the throt­tle with some lock on and you feel it im­me­di­ately tighten its line; tread a lit­tle more firmly and the rear quickly scooches round into mild over­steer. Its sud­den tran­si­tion is char­ac­ter­is­tic of a short wheel­base, but it’s not un­safe, or in­tim­i­dat­ing; just a lit­tle more keen to play than you might ex­pect, like an ex­cited puppy. Per­haps the Z4 re­ally is a no-caveat sports car at last…

Ri­vals? The Z4’s tra­di­tional spar­ring part­ner, the Mercedes SLC (nee SLK), will soon be put out to pas­ture, and its re­place­ment is un­con­firmed. Audi’s TT Road­ster isn’t go­ing any­where, though, and in RS form is now a very po­tent (if numb-feel­ing) sports car. Jaguar’s F-Type is brim­ming with char­ac­ter and sense of oc­ca­sion, if not per­ceived qual­ity. And the Boxster and its tin-roofed Cay­man twin, are hardy – and hard to beat – peren­ni­als.

The top-dog Z4 M40i will be sup­ple­mented by the sDrive 20i and sDrive 30i. Both will use the same 2.0-litre four-cylin­der turbo en­gine, with 196bhp in the 20i and 256bhp in the 30i. De­spite early ru­mours of all-wheel-drive ca­pa­bil­ity, all Z4s will be rear-wheel drive, and all use an eight-speed torque-con­verter auto gear­box (although a man­ual 20i will join the range in July as the en­try-level Z4). New road­sters are an in­creas­ingly rare breed but BMW’s en­gi­neered this one like it means it: trick dampers, race­car track widths, a peach of an en­gine and, in­side, its lat­est dig­i­tal in­stru­ment clus­ter, as seen in the 3- and 8-se­ries, plus the lat­est iDrive 7.0 in­fo­tain­ment sys­tem. It’s en­gag­ing and sear­ingly quick, and if it’s a lit­tle too com­fort-bi­ased then a meet­ing with a handy mid-en­gined Porsche will soon show up any dy­namic short­com­ings… And what’s this, an in­com­ing call from CAR’s Ge­org Kacher, wait­ing for me just up the road in an idling Cay­man… Over to you, Ge­org.4

No doubt­ing the front-en­gined lay­out, but the lump’s tucked well back at thebulk­head

Straight-six o ersau­ral plea­sure where a Porschefour can­not

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