What’s quicker, a 335d or its petrol-powered equivalent? We put standard and tuned 335s throughtheir paces at Bruntingthorpe Proving Ground to find out Words: Luke Wood Photos: Malcolm Griffiths/Max Earey

FUEL

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Le Mans racers are doing it, Touring Cars aredoing it and with the world the way it is atthe moment it would come as little surpriseif Formula 1 doesn’t follow suit in the nottoo distant future either.

It seems that diesel is taking over the world andit’s not just the race fraternity that’s benefiting either,because all the high-end technology that has workedso well to claim all those trophies is inevitablyfiltering down to the forecourts, and this means thatit is no longer dull to have a D on the back of yourcar, but desirable instead. In fairness, BMW seems tohave steered clear of going the way of the dieselwith its motorsport programme, (although with SEATdoing so well in the WTCC with its Leon you have towonder how long it will stick with the 320si) so in away it’s surprising that it is leading the way in termsof producing the meanest and greenest diesel roadcars on the planet. Engines such as the twin-turbo,four-cylinder unit in the 123d, the third generation 3.0-litre common rail in the facelift 330d and themighty twin-turbo ’six that lives under the bonnet ofalmost all top end models in the BMW range are in a class of their own.

Not only are they becoming increasingly refinedbut they manage to deliver a blend of performance,flexibility and economy that more often than not putsthe petrol alternative to shame. The day of the dirtydiesel is long gone and the agricultural horrors of thepast are now just a distant memory.

But are diesels really the future and can they everreplace petrol powered cars as the defaultperformance option? For most die-hard petrol heads,fast diesels are merely a way of making the dailycommute marginally less painful and when they’renot being used mid-week they double up as load-luggers or cars that are handy for towing somethinglightweight and high-revving to a trackday.

These are the kind of people that BMW is going tofind hardest to convince that torque, not brakehorsepower, is the way forward and while this mighttake some doing, we feel that the time has come toat least start considering the possibility.

Which would you say is the most potent car forexample, the 335i with 306hp and 295lb ft or the335d with 286hp and 420lb ft? Both have six-cylinders, a brace of turbos, near identical capacityand a top speed that is limited to 155mph and both

Do you pay thepremium for dieselpower in your 335,with tons of torqueand a greater rangebetween fill-ups, or…

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have the ability to see off the sprint to 60mph inunder six-seconds. The way they go about it thoughis quite different, with the 335i relying on a broadspread of revs to muster its performance and the335d leaning on a mountain of torque that threatensto rip the run-flats from the rims at just 1750rpm.

Under everyday conditions, it’s very easy to beswayed by the character of the petrol model. There’sthe option of a six-speed manual gearbox for a start,something that is usually high on the wish list of themore enthusiastic driver, but it’s the engine note thatreally helps to sway things. The latest engines aregetting better, but noise is the diesel’s perennialproblem. Let’s face it, when was the last time youwound down the window in a tunnel to soak up thesoundtrack from a 320d – hmmm, clattery.

If you can learn to live with this however, then thegap in performance is actually very small and interms of real world driving the diesel’s torque countsfor a lot. The sprint to 60mph looks good on paperbut being able to overtake three lorries and a tractoras quickly as possible is sometimes more relevant.

All of which brings us to Bruntinghtorpe ProvingGround for a 335 showdown to end all showdowns,

an opportunity to see whether diesel or petrol packsthe biggest punch in a straight line dash to 100mph,which is most effective when accelerating from60mph to 100mph and, as a bonus, which is thequickest over a lap of a circuit.

To make things interesting we’ve decided to mix itup a little by including a selection of readers’ cars torun alongside our pair of press vehicles and to reallyadd some spice we’ve invited along a tuned exampleof each to see how much can be gained from a re-mapped ECU. It may not be everybody’s cup of tea,but both the petrol and diesel 335 have hugepotential hidden away inside their electronics and bytapping into the ECU you can expect large gains tobe had in both BHP and torque. Companies such asEvolve Automotive for instance offer just such aservice, unearthing an additional 54bhp and 59lb ftin the 335i and a further 44bhp and 73lb ft in the335d for £1000 and £599 respectively. It’s a simpleand painless modification carried out via the OBDport and in addition to being undetectable, it comeswith full warranty cover as well.

Before we get to these though, we take our timeto set some benchmark figures in the press cars, and

For most die-hard petrol heads, fast dieselsare merely a way of making the dailycommute marginally less painful

…do you go down thepetrol route, with

more revs, a manualgearbox and a proper

soundtrack from thetwin-turbo ’six?

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Not only is it staggering to find such pacelower down the 3 Series range, but animpressive opening salvo toward the diesel camp as well

are immediately taken aback at just how conservativeBMW has been with its official statistics. Storming offthe line to 60mph in 5.1 seconds, our manual 335iobliterated the quoted 5.5-second to 62mph timeand took just 7.4 seconds more to crack the ton.These numbers are normally the reserve of M cars,so not only is it staggering to find such pace lowerdown the 3-Series range but a worryingly impressiveopening salvo toward the diesel camp as well.

In response the 335d thunders up Bruntingthorpe’srunway in an incredible 5.7 seconds, againsignificantly quicker than the officially quoted time,before blitzing the 100mph barrier in 13.7 secondsdead. Fast, hugely so for a diesel, but not quite fastenough and it’s first blood to the petrol posse.

Round two and it’s the turn of our brave readers,all of whom have volunteered their personal cars tobe launched into the fray. First up is John Gray, whokeenly hands over the fob to his 335i Touring, awagon that is used daily for work and used hard. In

the short time he’s had the car John has put threeyears of mileage on the clock and is already on hissecond set of turbos, so if this doesn’t count as awell run-in example then nothing will. Run in it maybe, but it also proved particularly difficult to launchcleanly and after several aborted runs we decidedthat the clutch had probably had enough so wedecided to call it a day at 5.6 to 60mph and 13.6 to100mph. Not bad for a miley workhorse, and prettymuch bang on the manufacturer quotes as well, buttry as we might we just couldn’t match the ballisticperformance of the press car.

In contrast, the 335d of Kevin West actuallymanaged to raise the game for team diesel, posting astonking 0-60mph of 5.6-seconds, equal to theTouring and a tenth better than we managed with the335d press car. By 100mph though, Kevin’s car wasreally on the boil. With a 13.3-seconds flyer it provedto be faster still than the press car and mostimportantly, three tenths faster than the 335i.

With the scores levelled it was down to the Evolvetuned bad boys to slug it out for the third and finalround. With something in the region of 350bhp and350lb ft of torque on tap the deciding factor herewas how easy it was going to be to launch ChrisBurridge’s car without frying the transmission orevaporating the rear tyres, so it was perhaps not toosurprising that the initial 0-60mph did not quitematch the earlier benchmark set by the press car.Once on the move though and with traction less ofan issue, the Evolve 335i really came into its ownand by 100mph it was almost a second ahead.

With a seemingly impossible target to beat theEvolve 335d of Julian Marshall was lined up. Withalmost 500lb ft of torque at its disposal the bigquestion again was just how effectively the standarddifferential, tyres and gearbox were going to be ableto cope. Several techniques were employed in orderto get the 335d off the line in the most effectivemanner, including holding the car on the brakes with

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Our readers are a brave bunch. Not only didthey volunteer their cars but they allowed

them to be abused by the Deputy Editor.Above and beyond, gentlemen…

The pros and cons of both the 335d and335i were discussed at length. Actually,we were just talking about what to have for lunch

various amounts of revs dialled in, semi-autolaunches, full automatic launches, launching withoutany holding on the brakes – all of which madesome, but not much difference to the final outcome.

Which was that while the tuned 335d wasmonstrously fast to 100mph, nearly a second andhalf more than the quickest of the standard cars, itstill didn’t quite have enough to outdo its petrolpowered rival. With these last two cars we’re talkingabout a mere tenth of a second in places, and whilethat may not seem like much, it’s enough to makethe difference between coming first and second. Sothat’s settled then, diesels may be getting close, butpetrol is still the way to go, whether it’s in standardform or a more highly tuned state. Not quite,because the 335d has one last trick up its sleeve.

While the straight line figures of the standardversus Evolve tuned 335s are certainly revealing,there’s a limit to the amount of abuse we’re willingto inflict on our readers’ cars. We’re a caring bunch

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of individuals you see, and when we invite peoplealong to places like Bruntingthorpe, we like to seethem leave at the end of the day with all theimportant bits of their vehicles still attached.

So in the interest of science, we thought we’d givethe press cars one last workout by driving them flatout around a circuit, somewhere with fast straights,challenging corners and not too much to hit should itgo wrong, to see which would set the fastest lap.

Conveniently, our sister magazine PerformanceCar happens to have just such a track laid out atBruntingthorpe Proving Ground and as those boysare always willing to throw caution to the wind in thesearch of a hot lap, we handed over the key fobs toits chief Stig, Deputy Editor Chris Knapman, to seehow the two hot 3 Series would fair.

Positioned in our makeshift pitstop, bets weremade as to which would be the quickest of the two,the torque happy Derv demon, or the silky smoothpetrol and as the latter was armed with a ‘proper’manual six-speed it’s fair to say that the 335i was theinitial odds-on favourite. And, after the first flying lapsit certainly seemed as though the diesel was going tohave its work cut out as the singing straight-six roared

its way around the vast open spaces of the LeicesterProving Ground, picking up huge speed on the long,flat straight and flinging itself into the fast bends withtyre screaming conviction. The 335d, handicapped byits slush ’box would have no chance. Imagine oursurprise then when the results were downloadedfrom the timing gear. We checked, we doublechecked and we checked again but there was nogetting away from the truth of it. The diesel had wonby just 1/10th of a second, and again it was alldown to its prodigious twist. According to Knapmanthere was nothing in it under braking and in cornerentry, it was just that the 335d had so much moreshove on the exit. So there you have it, 1m22.8seconds for the 335i and 1m 22.7 for the 335d.Diesel wins, petrol loses. And what is more incredibleis that this winning time is only 2.4-seconds shy ofthe 1m 20.3s that Performance Car recorded for theE90 M3, in similar conditions earlier in the year.

Should we start worrying about a diesel poweredM car in the future? You heard it here first… ●

CONTACT: Evolve AutomotiveTel: 0870 0850 111 Web: www.evolveyourcar.com

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13335i’s manual ‘boxmore satisfying touse than diesel’sautobox but stillno quicker

3rd gear in335i, 4th in335d

Balance throttlehere, extra weightin diesel’s nose not obvious

Short shift up onegear then flatthrough seven.335d’s torquereally starts to show

Turn in almost flatand hold tight. Bothcars equal here

START/FINISH

Turn in slowly, waitto pass apex before

getting on the powerto the finish

Small slide intonine. 335d slides

as well as 335i

Both cars excellent on the brakes, butagain 335d has more punch on exit

PERFORMANCE FIGURES335i* 335d* 335i 335i** 335d 335d**

0-10 0.7 0.6 0.6 0.8 0.5 0.6

0-20 1.4 1.3 1.3 1.7 1.2 1.3

0-30 2.1 2.2 2.1 2.3 2.0 2.1

0-40 3.2 3.1 2.9 3.0 3.0 3.0

0-50 4.0 4.2 4.4 4.2 4.1 3.9

0-60 5.1 5.7 5.6 5.2 5.6 5.3

0-70 6.8 7.2 7.7 6.4 7.0 6.5

0-80 8.4 9.1 9.3 8.4 8.9 8.1

0-90 10.2 11.2 11.2 10.0 10.9 9.9

0-100 12.5 13.7 13.6 11.7 13.3 11.9

60-100 7.4 8.0 8.0 6.5 7.7 6.6

* Press car ** Evolve tuned car

CHRIS SAYS:335i felt faster butthe 335d’s torquewas astonishing

Lap times: 335d 1 minute 22.7 seconds335i 1 minute 22.8 seconds

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