[Steved]

I have been forming my thoughts over on another forum as I decide which engine to opt for in my X6, and thought some of my findings may be useful to those here on E90Post.

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I had on loan today a 335d MSport Touring and a 335i MSport Convertible. The 335d had 7500 miles, whereas the 335i was new with just 330 miles on the odometer. I drove the 335d first for 3 hours, then swapped over to the 335i for another 3 hours covering a variety of roads A, B, and Motorway with some city driving through the outskirts of Birmingham.

I covered around 200 miles in each, the 335d averaging just over 40 mph with a consumption of 26.6 mpg, whilst the 335i averaged 55.9 mph with an overall consumption of 21.7 mpg. Both were fully extended as their makers intended and I didn't spare the horses, so these are definitely 'real world' economy figures although I covered slightly more motorway miles in the 335i than the 335d.

Now for my impressions. I was comparing the two engines on the basis of four criteria; actual performance, ease of delivering usable performance, aural enjoyment, engine character.

In terms of 'actual performance' there was little of any note between them, they were both equally as quick but they achieve their speeds in entirely different ways. The 335d is not fitted with a temperature gauge (that I could find), but I noticed its performance tailing off after the first 2 hours of driving, not massively so, but the edge was lost and it seemed to be shy of some torque. The 335i was more consistent, but I am not sure if that was symptomatic of just these cars I drove or the models themselves.

I greatly preferred the 335i though at low revs. The 335d really languishes at low revs, feeling more like an un-boosted diesel for those first few seconds before the turbos kick in, this is nowhere near as noticeable as a 2.0td or even the single turbo 3.0d, but it ‘is’ noticeable and makes it feel initially stodgy. The 335i by comparison has torque from the get-go and pulls cleanly and crisply away from junctions. So, for driving around town the 335i was the one I would have chosen.

In terms of ‘usable performance’ the 335d scored the highest. There is strong torque from around 2000 rpm through to 4000 rpm which means that most of the time it has an answer available for whatever you need, without requiring a change of gear. The 335i I drove seemed slower than the one I’d driven before, but then it was still shy of a few miles and was also carrying the 200kg heavier body shell of the Convertible. It behaved much more like a NA engine needing revs to deliver its performance, although as the miles increased its acceleration felt stronger. Whereas the steering wheel paddles felt pointless in the 335d, in the 335i there was reason to change gear and optimise its performance. Whether that’s a strength or a weakness will depend on what you want from a car, but it certainly made the 335i the more ‘interesting’ engine to drive.

In terms of ‘sounds’ the 335i won my favour without even breaking into a sweat. This is actually quite a significant criteria when comparing these two engines for a number of reasons. Firstly, I have never liked the diesel engine’s death-rattle at low revs and whilst the 335d is a smooth diesel it still sounds industrial and functional at low revs and under light-load before the turbos kick in. Driving around town and through narrow side streets this was a sound that I tried to minimise in the 335d, whereas the 335i sounds considerably better at low revs, delivering a quite exotic 'yowl' from its exhaust and continuing with similar tonal changes as it rises through the revs. So, I found myself indulging in the noises made by the 335i but trying to avoid the ones made by the 335d. For a car with sporting pretensions that’s a significant point to note. The 335d is actually quieter than the 335i under cruising conditions, and even under hard acceleration the diesel is the quieter of the two, however I never found anything actually endearing about the sound of the 335d. it’s one of those engines that ‘does-what-it-says-on-the-tin’, again perhaps betraying its more functional origins.

So, overall the 335d was at its best aurally when at its quietest, whereas the 335i appealed for the orchestra of sounds that it made. This again heightens the reference for a sporting car, which is surely characterised by how good it should sound.

Finally in terms of the ‘character’ of each engine; the 335d impresses for its locomotive shove in the back which then continues on as if it will never stop, but when it does stop its like the lights being switched on at a New Year’s party. Games are over, everybody go home. What seems unstoppable suddenly comes to a halt and for a moment (until the next gear engages and boost is re-engaged) you wonder if you imagined its strength. This pause in acceleration was more noticeable in the 335d, whereas the 335i showed that familiar petrol engined theme of the rev limiter stopping an engine that could have carried on for another few hundred revs. I found myself consciously changing up before the rev limit in the 335d just to avoid the disappointment. Also for me the 335d was a one trick pony, it had great strength from mid-range onwards but that’s all it had. I respected its strength but I never found myself endeared to it. The 335i although feeling weaker, countered with bucket-loads more character, a far more endearing sound and a genuinely sporty (and exotic) feel.

When I brought each car back I felt I had got to grips with the 335d, felt it would make a good companion on a journey but did not feel any further need to drive it. Whereas I was still playing with the 335i, learning more about its torque curve and which gear to be in to maximise its performance, whilst enjoying bouncing the sounds of its exhaust against buildings and parked cars. I did however find myself tiring (slightly) of revving the 335i and the unwelcome increase in decibels this produced, just a little more torque would make this engine near perfect.

So, which would I have chosen for a 3-series? I would have chosen the 335i. It had more character, and a sporty character at that, was quick enough and sounded just how a sporty car should. The 335d just felt too functional by comparison. I found myself weighing up ‘effortless torque’ against ‘character’ and preferred character, and also thought that the 335i would be the more endearing car to own over a longer time-period (where most of us suffer from boredom and pangs of vehicular promiscuity). But in an X5 I would probably choose the 35d engine, because such a functional locomotive quality would be both more necessary and in keeping with its utility nature.

But I’ll admit that after 400 miles or so of driving I’m not sure I’m any closer to deciding what would work best on an X6. I would prefer the 35i engine with more torque, which is perhaps what would be achieved with an ECU mod, and whilst I am sure the 35d engine would work fine I am quite concerned that I would become bored of its singular personality quite quickly.

Unlike in a petrol engine the torque curve of the 35d engine is mainly descending, what this means is that once you get that hit of torque at low revs, the performance (i.e. rate of acceleration) never gets any greater. So the feeling you get is like a giant hand pushing you along, but none of the feeling in a really powerful petrol engine where the rate of acceleration seems to be increasing exponentially. Most of us have recognised that feeling as being the essence of sportiness, so its quite hard to categorise the feeling that the powerful TDi engines provide.

I personally concluded that it doesn't feel sporty, but it is very effective.

One other characteristic is throttle response. With the 335d the throttle response was as if pressing the pedal through a soft pillow, eventually it would respond but nowhere near as instantly as the 335i petrol. It was the 335d engine that felt turbocharged, whereas most of the time the 335i engine just felt normally aspirated, but the 335d did feel like the 'larger' engine and provided you did not rev them then you would form an opinion that the 335d was the faster car.

After my long drive today I hopped into my RS4 and immediately appreciated its ability to provide the same (if not more) usable torque as the 335d but with the breadth and control of the 335i. The ideal solution for me therefore is an engine with lots of torque 'and' a good ability to rev (i.e. the best of both worlds). I suspect that BMW's new X50i engine (407bhp/450lb/ft) will provide this.

[JaMa]

Great write up, thanks for your thoughts.

Unfortunately we have to wait until September 08 in the US to find out what the 335d feels like.

J

[Kiemyster]

yes, excellent write up. i really can only say: you dont have much of a choice.... you just gotta wait for it to come. i dont think the 335d should be anything radically different, but you never know.

keep in mind, BMW is attributed to sportiness, and i dont think they would allow a fuck up for a 3 series. i just dont think they would ever, ever let it happen.

[John 070]

Since Fri., regular unleaded dropped 10 cents per gallon. Premium dropped 4 cents (econ majors could explain elasticity). Diesel went up another 4 cents, with the spread being about 68 cents. Don't really understand how a 335d is gonna make it in the US with the current fuel prices. Every time the fuel door opens it's 50-70 cents more per gallon, doesn't make a lot of common sense. Less performance, greater fuel cost, higher torque. 1 out of 3 aint bad?

[ojungoon]

to OP.... great write up

You've good some nice cars... MB AMG, Audi RS and BMW M3 CSL
damn!!!!
PIC'S PLEASE~~~~~~~~~

[voltron1011]

Awesome preview for all of us Yanks that haven't driven one yet.

[Lassaxi]

Originally Posted by John 070

Since Fri., regular unleaded dropped 10 cents per gallon. Premium dropped 4 cents (econ majors could explain elasticity). Diesel went up another 4 cents, with the spread being about 68 cents. Don't really understand how a 335d is gonna make it in the US with the current fuel prices. Every time the fuel door opens it's 50-70 cents more per gallon, doesn't make a lot of common sense. Less performance, greater fuel cost, higher torque. 1 out of 3 aint bad?

Just west of Boston, you can get premium for about $3.17 right now. Ultra low sulfur diesel is around $3.60.

Let's assume you drive 15,000 miles per year, and let's use the EPA city mileage estimate of 19 mpg for the 335i, and BMW's estimated city mileage of 23 mpg for the 335d. Here's the total annual fuel cost with those numbers:

335i = 15,000/19mpg*$3.17 = $2,503
335d = 15,000/23mpg*$3.60 = $2,348

Assuming those mileage figures are in the ballpark, the diesel still has the lower annual fuel cost, at least for now.

By the way, for the OP: thanks for the thoughtful writeup.

[Steved]

Originally Posted by ojungoon

to OP.... great write up

You've good some nice cars... MB AMG, Audi RS and BMW M3 CSL
damn!!!!
PIC'S PLEASE~~~~~~~~~

Thanks. Here's a pic of some of my toys..

[neo871]

holly shit!!

[stressdoc]

335d = practical, effective, functional, responsible
335i = sporty, fun

Kind of like the stereotyped bi-polar German personality. Bavaria as manic, wild; Hamburg and the north as conservative, repressed.

Diesel prices here are 10-20 cents higher than premium. No idea why. They should be 50 cents less. Politics is weird.

[hl0m4n]

Originally Posted by Steved

Thanks. Here's a pic of some of my toys..

nice collection of cars man. more pics of the CSL

[ElCapitan]

Originally Posted by Lassaxi

Just west of Boston, you can get premium for about $3.17 right now. Ultra low sulfur diesel is around $3.60.

Let's assume you drive 15,000 miles per year, and let's use the EPA city mileage estimate of 19 mpg for the 335i, and BMW's estimated city mileage of 23 mpg for the 335d. Here's the total annual fuel cost with those numbers:

335i = 15,000/19mpg*$3.17 = $2,503
335d = 15,000/23mpg*$3.60 = $2,348

Assuming those mileage figures are in the ballpark, the diesel still has the lower annual fuel cost, at least for now.

By the way, for the OP: thanks for the thoughtful writeup.

Don't forget that the 335d will be more expensive to get than the 335i.

[dagjohnsen]

This is the best description of diesel vs gasoline I have ever seen, you should get a job in a car magazine

I have had gasoline cars all my life, now it has been 6 months with diesel.
I love the power but miss the spirit

[John 070]

Originally Posted by Lassaxi

Just west of Boston, you can get premium for about $3.17 right now. Ultra low sulfur diesel is around $3.60.

Let's assume you drive 15,000 miles per year, and let's use the EPA city mileage estimate of 19 mpg for the 335i, and BMW's estimated city mileage of 23 mpg for the 335d. Here's the total annual fuel cost with those numbers:

335i = 15,000/19mpg*$3.17 = $2,503
335d = 15,000/23mpg*$3.60 = $2,348

Assuming those mileage figures are in the ballpark, the diesel still has the lower annual fuel cost, at least for now.

By the way, for the OP: thanks for the thoughtful writeup.

In your assumption, if the diesel is $150 less per year on fuel, where's the break-even if the diesel vehicles costs more to begin with? If we stick with 19 mpg vs. 23 mpg, the more one drives the more one saves. Sounds about right. But with the spread increasing between diesel and unleaded, the savings is also diminishing. I don't think anybody will argue that the diesel is less of a sports car, the idea is to reduce weight, not increase it.

If diesel cost less than unleaded, it would appeal to a broader audience.

[AndreyATC]

I think the difference in MPG is greater between these two
You'll feel it even more with freeway driving
It would be 27 vs 40MPG or so

[ElCapitan]

Originally Posted by John 070

In your assumption, if the diesel is $150 less per year on fuel, where's the break-even if the diesel vehicles costs more to begin with? If we stick with 19 mpg vs. 23 mpg, the more one drives the more one saves. Sounds about right. But with the spread increasing between diesel and unleaded, the savings is also diminishing. I don't think anybody will argue that the diesel is less of a sports car, the idea is to reduce weight, not increase it.

If diesel cost less than unleaded, it would appeal to a broader audience.

Exactly. Well said.

[IDreamofBimmers]

Originally Posted by Steved

Thanks. Here's a pic of some of my toys..

Holy
What do you do??
I wanna do the same thing cuz that's a sweet collection!!

[Lassaxi]

Originally Posted by John 070

In your assumption, if the diesel is $150 less per year on fuel, where's the break-even if the diesel vehicles costs more to begin with? If we stick with 19 mpg vs. 23 mpg, the more one drives the more one saves. Sounds about right. But with the spread increasing between diesel and unleaded, the savings is also diminishing. I don't think anybody will argue that the diesel is less of a sports car, the idea is to reduce weight, not increase it.

If diesel cost less than unleaded, it would appeal to a broader audience.

I'm not sure what the pricing is for the 335d, but definitely true that, at current gas/diesel prices, it will take a while to make back the difference in initial purchase cost. If you drive more, or keep your car longer, or if diesel prices fall back to where they should be vs. gas prices, the diesel will do better. But, this is basically the same type of problem that hybrids have right now. They way market dynamics are working in the U.S. right now, it takes forever to recoup the higher initial outlay for the fuel-saving technology.

[ElCapitan]

Originally Posted by Lassaxi

I'm not sure what the pricing is for the 335d, but definitely true that, at current gas/diesel prices, it will take a while to make back the difference in initial purchase cost. If you drive more, or keep your car longer, or if diesel prices fall back to where they should be vs. gas prices, the diesel will do better. But, this is basically the same type of problem that hybrids have right now. They way market dynamics are working in the U.S. right now, it takes forever to recoup the higher initial outlay for the fuel-saving technology.

I think most of the hybrids buyers are never making the money back. More expensive initial purchase, maintenance and inssurance. I see the only benefit they do is reducing somewhat green gas emission and clear their conscience IOT exhube an "I am holier than thou." attitude.

[AndreyATC]

Dont they have tax brake on purchase as well?

[Dave_3]

Originally Posted by John 070

In your assumption, if the diesel is $150 less per year on fuel, where's the break-even if the diesel vehicles costs more to begin with? If we stick with 19 mpg vs. 23 mpg, the more one drives the more one saves. Sounds about right. But with the spread increasing between diesel and unleaded, the savings is also diminishing. I don't think anybody will argue that the diesel is less of a sports car, the idea is to reduce weight, not increase it.

If diesel cost less than unleaded, it would appeal to a broader audience.

In Europe a like-for-like specced 335D and 335i were separated by barely $500 (think the 335D is 50kg heavier). So the price difference is inconsequential. I'm pretty sure with haggling you could match the 335i.

The fact you can actually easily save that with the 335D's economy is just one of the bonuses.

But if you really are interested in cost per mpg, why did you buy a BMW ? There are just as many functional cars around that deliver better economy for a far smaller outlay. I think all of us here have bought the car we wanted because of varying reasons - and economy was not the sole deciding factor.

So ... you may well choose a 335D, for the same reasons you choose a 335i. Greater performance. The added bonus is that the 335D returns simply stunning economy for the power/torque on tap. Nobody rationalises buying a 335i on its economy or money they will save compared to a lesser model (because you won't) - why harp on about the 335D like that ?

I agree with Steve, if you want to tharsh around everwhere and love high revs and that aural tingle, then the 335i is the one for you - and you'll love it. However, if you want 90% of the power available in everyday driving conditions mated with very good economy get the 335D. For some that driving style will be the reason alone they are sold on the 335D, and probably more representative of the majority of BMW drivers (whereas this forum is skewed more to the younger driver).

Horses for courses.

Soon you will have the choice ... that can't be bad !

I've had my E92 335D for a year now. Never fallen below 32mpg. Pretty much exclusively city driving. Thunderous torque. Just great.

D.

[demosthenes]

OP: Thanks for the great write-up.

I appreciate how you covered all the bases including sound. How a car sounds is a big deal to most of us and it doesn't get enough attention. This is especially true with stick shifts because we rev them higher.