Diesel vs Petrol

motorguy

sebdangerfield wrote: »

A better comparison is a turbocharged diesel and a turbocharged petrol.

No its not. You're not comparing like with like.

Can you show me where theres a 2.0 Turbo petrol mondeo in say, 'Edge' trim to match the 2.0TDCI?

Or can you show me a 2.0i Turbo 3 series BMW to match the 2.0TD?

The combination of the turbo and the diesel engine is merely how the TD engine goes about getting its power. In the same way as most petrol cars use a fuel injection system.

Therefore the real world choice and comparison that people have to make when buying say a mondeo is 2.0i versus 2.0TDI. They wont be looking at a 2.0TDI and thinking hmm, now wheres that 2.0 Turbo petrol car?

motorguy

For all this talk of oh oh petrols are simply so much better because you can get a higher power output, i'd say the vast bulk of people on here, and out there in the real world, are probably driving something with maybe 100-130BHP if even that. And when you're in that realm, i cant think why you'd buy a petrol as the diesels are that good.

sebdangerfield

Are you Mr. Mondeo!? One man forum!

I was simply discussing engines, not cars. I did that because some people on here, say mundaino drivers, are a little tetchy about having a bland car and so to keep the peace I was talking about engines directly. To use your argument.... could you show me the Noble diesel engine please so I can compare also? No, thought not, thats why were discussing engines instead of models, trim etc.

So, discussing engines. I thinks comparing a normally aspirated petrol to a common rail turbocharged diesel is not in any way a direct comparison. In the post I made earlier I made it clear that many of the benefits of the diesel in this comparison are closer met when the petrol is blown and has the direct petrol injection like the FSI audi developed. Blown petrol engines have more torque, like diesels. Common rail and fsi petrol engines are more economical like diesels. Either way the petrol is generally more powerfull.

I agree that most people don't use vehicles with any more than 100-130 bhp but this is a motoring forum and, like me, there are many people on here who do have powerfull cars and enjoy the discussion. Top gear may as well only report the new signum or the other rep wagons if thats the case. Equally, there are some lovely Butlin's sites around the UK yet thousands fly all the way to tuscany each year to spend a week or two. Maybe not everyone wants average?

Rolandtheroadie

pgilc1 wrote: »

But you're not comparing like with like though. The average mondeo buyer have the choice between the 2.0TDI and the 2.0i petrol version.

The diesel variant will be more driveable, offer better economy, and have a better residual value - and to get that they lose out slightly in the 0-60 traffic light grand prix to the petrol version. I think most people look at that and its a no brainer for the diesel.

Totally agree with you need to compare like for like. BUT a 2.0 Mondeo compared to a same spec Mondeo 2.0 petrol is quicker 0-60. And only £145 Road Tax (last time I taxed it, may be £155 now) compared to £215 for the 2.0 petrol.

The BMW/AUDI reference needs to compare a 3l Audi petrol to a 3l Audi Diesel and vice versa for the BMW.

motorguy

sebdangerfield wrote: »

Are you Mr. Mondeo!? One man forum!

I was simply discussing engines, not cars. I did that because some people on here, say mundaino drivers, are a little tetchy about having a bland car and so to keep the peace I was talking about engines directly. To use your argument.... could you show me the Noble diesel engine please so I can compare also? No, thought not, thats why were discussing engines instead of models, trim etc.

EXACTLY - by taking an extreme like a noble then you're not comparing like with like. How many people on here drive nobles???

sebdangerfield wrote: »

So, discussing engines. I thinks comparing a normally aspirated petrol to a common rail turbocharged diesel is not in any way a direct comparison. In the post I made earlier I made it clear that many of the benefits of the diesel in this comparison are closer met when the petrol is blown and has the direct petrol injection like the FSI audi developed. Blown petrol engines have more torque, like diesels. Common rail and fsi petrol engines are more economical like diesels. Either way the petrol is generally more powerfull.

You may well speak of engines - but people do not buy their cars based on whether or not it has a turbo on it - they buy it because it suits their needs. Someone who is looking at a 2.0TDCI 130BHP mondeo wont say, oh i'll spend and extra £5K and go for the 2.0 Turbo 220BHP version (if one existed). They will compare it to the next nearest (and purposely so) petrol variant.

sebdangerfield wrote: »

I agree that most people don't use vehicles with any more than 100-130 bhp but this is a motoring forum and, like me, there are many people on here who do have powerfull cars and enjoy the discussion. Top gear may as well only report the new signum or the other rep wagons if thats the case. Equally, there are some lovely Butlin's sites around the UK yet thousands fly all the way to tuscany each year to spend a week or two. Maybe not everyone wants average?

Ok, summarising.

Will a turbo petrol engine produce a higher specific output that the same CC of turbo diesel. Yes.

But i dont know what that really proves?

motorguy

scotsman4th wrote: »

Totally agree with you need to compare like for like. BUT a 2.0 Mondeo compared to a same spec Mondeo 2.0 petrol is quicker 0-60. And only £145 Road Tax (last time I taxed it, may be £155 now) compared to £215 for the 2.0 petrol.

The BMW/AUDI reference needs to compare a 3l Audi petrol to a 3l Audi Diesel and vice versa for the BMW.

Thats even better then. And it shows the effort that manufacturers are putting in to diesel development.

Yes, for every 3.0i BMW there is generally a 3.0TD version - thats my point.

The direct comparison for a BMW 320d is a BMW 320i - ie, BMW do NOT make a 2.0T because they know its not what their market wants.

motorguy

sebdangerfield wrote: »

Equally, there are some lovely Butlin's sites around the UK yet thousands fly all the way to tuscany each year to spend a week or two. Maybe not everyone wants average?

Eh? Do you really think that Diesels v Petrol is like comparing Butlins to a foreign holiday?? That is pitiful. :rotfl:

Mate, there are now just subtle differences between petrol and diesels. Noise at startup and the way the power is produced the main differences. Offsetting that, you get oodles or torque and significantly better economy.

And thats about it. If you really really want power, then buy the car that suits you. Thats fine. Just because you drive a diesel doesnt mean your some sort of sub human.

Last time i wanted real power i opted for a 535d and remapped it to 340BHP and 500lb/ft of torque. It hit 0-60 in 5.5s and topped out at about 173mph. Oh and it did 37mpg.

My wife on the other hand has just bought a new Subaru WRX-S. 255BHP, 0-60 in 5.5s and gets 22mpg tops.

You pays your money you makes your choice.

Conversely, i'm doing big miles to work now and we're building a house, so i've a passat bluemotion that i've seen break 72mpg on the commute. I dont think that makes me any less of a 'driver' just because i want something comfy and economical for the morning drudge to work.

alo6

sebdangerfield wrote: »

tomstickland wrote: »

QUOTE]

The whole reason of the diesel tt is cheaper tax, cheaper bik and more mpg at the sacrifice of a second and a bit of acceleration.

the TT Diesel has 4 wheel drive i believe. (safer)

jaydeeuk1

We've put man on the moon, made computers that can emulate a mouses' brain, manipulate atomic structures, but we still can't make a family diesel engine that doesn't sound like its about to fall apart.

Having driven mostly smaller engined diesels, 2.0l or less, I can safely say I prefer the petrol variants.
IMO, diesels still have some way to go before they're as good as petrol engines. No doubt they will one day, as after all, diesel fuel contains more energy/gallon.
A mid 90's 2.0l turbo fiat coupe engine still trounces over any 2.0l turbo diesel (though to be fair, I hate turbo lag)
Petrol engines sound better and rev better imo. They're cheaper to repair and maintain/service. Even my little iq3, I only ever need to use 2nd gear. Accelerates all the way from 5mph to 65. In most diesels, you'd be in 4th gear already!

And top gear showed, in a straight line, the BMW 3.0 litre turbo diesel wasn't as quick as the 3.0 litre petrol.

motorguy

jaydeeuk1 wrote: »

We've put man on the moon, made computers that can emulate a mouses' brain, manipulate atomic structures, but we still can't make a family diesel engine that doesn't sound like its about to fall apart.

Having driven mostly smaller engined diesels, 2.0l or less, I can safely say I prefer the petrol variants.
IMO, diesels still have some way to go before they're as good as petrol engines. No doubt they will one day, as after all, diesel fuel contains more energy/gallon.
A mid 90's 2.0l turbo fiat coupe engine still trounces over any 2.0l turbo diesel (though to be fair, I hate turbo lag)
Petrol engines sound better and rev better imo. Even my little iq3, I only ever need to use 2nd gear. Accelerates all the way from 5mph to 65. In most diesels, you'd be in 4th gear already!

And top gear showed, in a straight line, the BMW 3.0 litre turbo diesel wasn't as quick as the 3.0 litre petrol.

Everything in your first paragraphs just demonstrates that we're wasting our time debating this, because petrol advocates dont want to hear and dont want to know.

RE: your final paragraph, have you a youtube link to it? Was it not the 535d against the 540i?