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Discussion Starter · #1 · (Edited)
A few years ago, die-hard petrol-heads like myself would never have considered a "smelly, smoky, noisy" diesel.

The engine game has now moved on and diesel powerplants have shown they really can win races (Audi R10 TDi - Le Mans) and power sports cars (Audi A5 3.0 V6 TDi & R8 V12 TDi) :D

Today, I find myself torn between ordering a "5" with a diesel engine or a petrol engine :(

I have read many conflicting reports, about diesel v petrol, from many different sources, but a few days ago I finally found some welcome clarity.

In a recent thread I saw that AntRS6 had switched from a Porsche Carrera to an A5 3.0Tdi, and I asked his about his decision to do so. Ant has kindly allowed me to post the PM which he sent me. Thanks Ant for your valuable contribution:

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AntRS6 wrote:

I had the same thought processes as you with regards diesel over free reving petrol engines. Having driven a multitude of both the diesel technology is getting better and better but still not quite as good as a really good petrol engine in spirited driving application IMO.

However, this is where I think the real problem is with the S5. Turbo charged cars give that lovely shove in the back (which you tend not to get in Normally Aspirated V8's, i.e. S4 & S5 etc...) unless of course it is something a little more revvy like the RS4. The 911 being 6 cylinder has a lovely shove as well, largely due to the tuning of the engine where torque builds up and then hands over to horsepower. The RS6 in standard form was ok, but being twin turbo, when it was modified it was awesome.

The engine characteristics of the S5 are pretty much the same as the outgoing S4. In so far as slightly touch the accelerator pedal and you get instant linear acceleration and it feels like the power is either on or off. The engine has no cammy characteristics, there's no variable valve intake, it's just flat grunt from 2K revs to 7K revs. As you climb the revs there is no change to the acceleration curve... it is flat throughout the rev range, making the car not feel particularly quick (although of course it is). I like a car that the harder you press the pedal, the more shove you get. Not so with the NA Audi V8 in the S4 and S5. You do get much of this with the A5 3.0 diesel although the rev range is much smaller! That's my first point.

The second point was how the car felt when driving. Handling, balance, transfer of weight and the ability to supply smooth inputs. The diesel was easier to drive, full stop. It feels lighter, it feels more progressive and the suspension seemed to be a better set up for the A5 than for the S5. The steering feel from the A5 was also better. In all I felt I knew where I was far more readily in the A5. The S5 lacked any feeling of urgency and was almost a little numb in the hands. I think this is probably due to keeping a distance for a probable RS5. The S5 seemed like a good touring car that would eat up mile after mile of smooth A roads and motorways, but if you wanted a smile on your face there is better out there for your money (say BMW 335i or M3). The S5 is probably only slightly more capable than the A5 but it doesn't feel like it is.

Third point, costs: Diesel returned 38mpg on the same test run where the S5 managed 20mpg. A5 will have better residual % than the S5. Servicing will be much cheaper on the A5 than S5. I am sure the S5 will suffer the usual issues that are brakes and radiators. Pads and discs at the front will be £500 - £600 and replacing (small) radiators about the same cost (these get stone chipped and then leak).

Fourth point: On A roads and Motorway (where I do most of my driving) the A5 was just as quick in terms of acceleration and felt more purposeful with it. Add to this the ability to get another 50bhp and 50nm torque (remap) from simple modifications it will probably make the diesel a quicker straight line car (at half the cost in mpg terms). The S5 has few modifcations avaialable but they won't really change the car at all. 10 - 15bhp and thats about it.

The S5 is a beautiful car and the noise it makes is glorious and whenever I see/hear one I am going to be wishing I had got one instead. But equally, if I were driving the S5 I would always be thinking I could have as much and if not more fun in the diesel for half the price!

It's a tough call, but the diesel makes much more sense to me in a world of increasing cost that relentlessly frowns upon speed. And lets be honest, can we really drive a car to its limits nowadays on the road?

Best of luck... I still want an S5 though! :D
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So what do you think ?
1. Are diesel engine sales set to totally eclipse petrol engines ? (see attached report)
2. In years to come, when you tell someone you have a petrol engine, will they say "I remember petrol engines" in the same tone we use when we say "I remember when you could smoke on a aircraft or in a bar" ?
3. Will engineers ever be able to widen the currently narrow peak torque rev range ?
4. Will diesels ever sound as good as a V8, or even a sweet V6 (eg R32) ?:)

Jump in with your thoughts on my questions or any of AntRS6's points above

Thanks everyone for making this such a great forum :)

Cheers

Bryce
 

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Bryce, thanks for opening up what will hopefully be an 'intelligent' and interesting thread with views and opinions and no bickering! I have posted on other threads about this topic as I am getting the S5 and not the diesel. I may dig up my other posts and link/paste them here, but for what it's worth here's my views:

I bought the S5 for the sound of the engine. And it is a beaut. Many regard this as the best V8 around today and one of the best ever. As a big Alfa V6 fan... I have to agree and I'm won over!!

For me, having tried them both as the rep wanted to sell me the 3.0TDI as he had one there to sell I really feel I would have to get used to 'short-shifting' and using the gears all the time. I'm sure I could, but after a day, it still frustrated. Sure, I loved the turbo 'surge' as I got this in my petrol 2.7 bi-turbo V6 but it was too short lived. I do like walking pace to 110 in one gear and 50 to 150 in top... this 'never ending' pull makes you appreciate the engine.

As for the V8, I was surprised, (Like Ant) there was not as much low down 'surge' as I was used to in my turbo V6 petrol, so the power build up was slower (and like Ant did not 'feel' as fast) but when it lit up... bloody hell! The diesel was nowhere near. I overtook a bus at 45mph in 4th and was over 100mph before I returned to my lane... and no gear change in the middle of the maoeuvre... the same for a big sweeping bend, where in the TDI I was forced to 'wait' on the acceletator until out of my corner as I needed to change gear but was cornering hard.

As for running costs... I've got my annual mileage down to 8k miles, by using public transport and cutting out unnecessary trips... that's greener than the average diesel driver and not too costly in a thirsty V8...

Therefore, I remain a petrol head... especially with that sound!!

I posted elsewhere about the difference between torque and horsepower, which may be useful for this thread at some point.

Right... to finish this tome...

Will diesel ever eclipse petrol sales? YES.

Will engineers widen the power range? Yes, a bit... it is happening all the time, but the fundamental limitations means it has nowhere near the same potential as petrol.

Will it ever sound as good? NO.

Thanks for listening!
 

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Thanks for sharing AntRS6's message, I was curious about his arguments.

I am nowhere close to an engineer nor a "sports" driver, just an average driver, so I cannot comment on the technical engine qualities. As I said in another thread, I preferred the A4 over the S5 for many reasons, but basically Ant's second and last points were the ones who won me over the A5.

That's my first diesel car, and I have to admit I miss the nice noise of a petrol engine. But for a diesel, it's quite nice too (compared to other diesels I could hear before !).

I think diesel has a potential to grow, and it's becoming more and more popular as constructors developp better and more economical engines. Will it one day replace petrol ? I doubt it, and sooner or later we'll need to find other fuel ressources...
 

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wismie... I've just noted in your signature that you have got Daytona Grey... damn... is that a standard colour in Switzerland? Would have loved it on mine (when it comes) but would have been another stack of folding beer tokens.

Anyway, back on topic. No worries on the post Bryce! Hope no one shoots me for it. But I did want to say that this was just my thought and decision process that eventually indicated the diesel was for me. If I was doing less miles per annum it would have been even more difficult to decide.

If you look in my signature, all of the previous cars I have owned have been petrol in either V8, flat 6, turbo 4or 8 pots. I have also driven a smattering of diesel VAG 1.9 - 4.2 tdi's and also the 2.0 turbo , 2.5 turbo, 3.0 turbo and 3.0 twin turbo diesel beemers. It does seem more is being invested in diesel cars than ever before and they are getting better. I was amazed at the 535d... get it lit and OMG! I am hoping with a bit of tweaking the new Audi 3.0tdi unit in the A5 could be as potent! Then, when I have done this I will come to a meet to try and compare with an S5. Ask Johny M, he is having his diesel tweaked tomorrow!

With regards noise... yes, there is little that compares to a V8. However. have you heard the sound of the Range Rover TD V8? It's the first time I've heard that V8 noise (that you get from a petrol V8) vague as it is, from a diesel. I know this is not an Audi, but it indicates that the better these diesels get, the more they are starting to mimic the petrol engines!
 

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wismie... I've just noted in your signature that you have got Daytona Grey... damn... is that a standard colour in Switzerland? Would have loved it on mine (when it comes) but would have been another stack of folding beer tokens.
AntRS6, no it's not standard color at all. You can order it through the Audi Exclusive program, thus additionall $$, which I did, and it is expensive (though worth it, and there will be at least 5-6 A4/S5 of that color in Switzerland). I guess it's the Geneva launch effect :D
 

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wismie, looks fab! Good choice!

Gone for Phantom Black with the tan brown hide and black headlining. If Daytona Grey had been available in the options list I would have ticked it, but it too is in the exclusive list for the UK spec and felt the money better spent elsewhere. But love the look of it.

The Black and Tan is a bit a strange one I know, but a friend had and RS6 in this colour scheme and I fell in love with it. A bit different. My wife isn't so keen, but hey... she can stick to her own car!
 

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Broadly agree with Ant's view. If my car was just for fun and personal use I would choose the S over the A. But mine is mainly for business and driving 30K+ miles a year, it makes sense to stick to the diesel. I wonder what the split is between personal and business ownership? I would guess that the S has more personal and the A more business. As for the increase in the number of diesel cars, I do my bit - I run a small business that has 12 company cars. I give my staff a free choice (within budget) - as long as it's a diesel!. Many other companies do this as well on the basis of lower running costs and higher residuals.
 

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I have always firmly been a petrol head, and at one time would have vehemently defended petrol against diesel. However the diesel game has moved on so far in the last 10 years that it's now a viable alternative for those seeking the performance angle.

For me, the very close performance times between the A5 3.0TDi and my old S4 4.2 V8 combined with 40mpg vs 20mpg was the deciding factor. Sadly I also could not have afforded any options on an S5 if I had ordered one - it would have had to have been just the basic S5 car (i.e. no B&O, no Nav, no cruise, non-metallic, etc, etc...) as £40k was an absolute limit to my finances. Then there's the issue of the insurance, which for my A5 is less than half what I used to pay for my S4.

Of course, I am missing the free-revving V8 as well as the endless acceleration - the diesel does give an enormous shove from the torque, but the rev limit is a bit of a restriction.
 

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I have always firmly been a petrol head, and at one time would have vehemently defended petrol against diesel. However the diesel game has moved on so far in the last 10 years that it's now a viable alternative for those seeking the performance angle.

For me, the very close performance times between the A5 3.0TDi and my old S4 4.2 V8 combined with 40mpg vs 20mpg was the deciding factor. Sadly I also could not have afforded any options on an S5 if I had ordered one - it would have had to have been just the basic S5 car (i.e. no B&O, no Nav, no cruise, non-metallic, etc, etc...) as £40k was an absolute limit to my finances. Then there's the issue of the insurance, which for my A5 is less than half what I used to pay for my S4.

Of course, I am missing the free-revving V8 as well as the endless acceleration - the diesel does give an enormous shove from the torque, but the rev limit is a bit of a restriction.
I chose the V8 for its power delivery and mostly down to its sound. I've had Diesel for the last 6 years and have no complaints about it, except I wish it sounded better and it reved a bit higher.

That said, if I was buying a 335 Coupe it would be the D and not the I, just thought the diesel was soo much better.
 

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I have always firmly been a petrol head, and at one time would have vehemently defended petrol against diesel.
Same with me; I never thought I'd put pen to paper on an oil-burner.:)

Diesel technology has come a long way, and Audi should be rightly proud of the diesel engines they have developed.
 

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This is all making me have last minute thoughts about diesel before I sign for the S on Monday :eek:
 

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How many miles are you doing p.a. Aiden?
 

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This is all making me have last minute thoughts about diesel before I sign for the S on Monday :eek:
Aiden,

Don't do it! You know that if either buying or running costs are both achievable for you, then you'd always regret not getting the S5! I wold dearly love an S5, but as I've outlined before, it's just that bit too expensive to buy, and part of my justification (to my wife!) for buying an A5 rather than a current A4 was the cheaper running costs and insurance, which offset the monthly outlays. My monthly fuel costs are roughly £150-£200 per month less running the diesel A5 against the S4, so it makes the monthly cost of the finance more bearable.
 

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12k to 15k miles - wise :eek:

I suppose part of my worry is that a V8 petrol might be a dinosaur in 2-3 years time the way diesel is progressing though? :eek:
 

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Aiden...

I am somewhat sympathetic with your view on the V8. Lovely as it is, the tech in it is fairly basic (by comparison to RS4/R8 V8 or even the old M5 4.0 V8 which managed 100bhp/litre). But the package is still an attractive one.

I wonder how many people who once they have stripped down their decision process went for the V8 largely because of the noise it makes. This was the main reason I bought the S4 and then the RS6! But the RS6 at 17mpg really started to hurt at £600 a month to fuel it.

At your kind of mileage though, £1,500 (UK prices) extra fuel per annum over the diesel ... £125 a month ... £29 a week ... £4 a day... for the V8 rumble! Turning the car over first thing in the morning to hear that sound... gotta be worth £2 of it!

Good luck
 

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Discussion Starter · #16 ·
£4 a day... for the V8 rumble! Turning the car over first thing in the morning to hear that sound... gotta be worth £2 of it!

Good luck
Ant, with that logic, you are doing a very good job of selling it to me too :D
 

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Ahhh... but I'm still riding on my hunch that the remapped 3.0tdi will prove the quicker car and cheaper (for me) long term... but... I do have my hat and tomato ketchup at the ready!
 

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Aiden...

I am somewhat sympathetic with your view on the V8. Lovely as it is, the tech in it is fairly basic (by comparison to RS4/R8 V8 or even the old M5 4.0 V8 which managed 100bhp/litre). But the package is still an attractive one.

I wonder how many people who once they have stripped down their decision process went for the V8 largely because of the noise it makes. This was the main reason I bought the S4 and then the RS6! But the RS6 at 17mpg really started to hurt at £600 a month to fuel it.

At your kind of mileage though, £1,500 (UK prices) extra fuel per annum over the diesel ... £125 a month ... £29 a week ... £4 a day... for the V8 rumble! Turning the car over first thing in the morning to hear that sound... gotta be worth £2 of it!

Good luck
That makes sense :)

Course the V8 here is € 10k more, spec for spec too? Extra depreciation woes too maybe?

Hmmm:eek:

<-------Scratches head some more :eek:
 

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Ahhh... but I'm still riding on my hunch that the remapped 3.0tdi will prove the quicker car and cheaper (for me) long term... but... I do have my hat and tomato ketchup at the ready!
I don't think the re-map will make the car quicker than the S. Adding 30bhp-40bhp to it will not even bring its 0 - 62 mph time down by 0.5 secs. Then if you bring 0 - 100 mph into it there is a big difference between the V8 and the TDI. After 60mph the V8 really starts to fly.

I'm not a 0-60mph fanatic but here are sometimes I found...

S5: (0 - 60mph = 4.8 secs) 0 - 100 mph = 12.1 sec
3.0 TDI: (0 - 60 mph = 6.4 secs) 0 - 100 mph = 16.6 sec
(Times are from Road & Track so people may find differenet times elsewhere, these were just the first ones I came across)

Main reason is that the quattro system seems to eat alot of the extra power a re-map gives. The only upgrade I think that will bring the TDI in line with the V8 is the ABT upgrade which includes the addition of the ABT turbo and you get 300bhp. But I'm sure mpg will also take a big hit from that too....not as much as the V8 but still. And the V8 rumble will always be missing from it.
 
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