Why is diesel so efficient

[turbonutter69]

They use a little less fuel but diesel is more expensive than petrol so does it really make a difference?
Plus economy doesn't just cover MPG.
Diesels are considerably more expensive to maintain.
Over say a 5 year period I dare bet there wouldn't be much difference in how much is spent on either petrol or diesel.

[Yugguy]

Why does everyone keep saying diesels cost more to maintain? We have two, in 6 years I've not had to do anything I wouldn't have to do on a petrol car.

[turbonutter69]

Maybe so but your service costs are more than the equivalent petrol version.
Plus if something does go wrong I'll bet it would be more to repair than the equivalent petrol version as well.

[Marc07]

Originally Posted by turbonutter69

Maybe so but your service costs are more than the equivalent petrol version.
Plus if something does go wrong I'll bet it would be more to repair than the equivalent petrol version as well.

Exactly ... but they do more MPGs than petrol and thats the point I was trying to make, fuel consumption diesel wins, repair cost petrol wins, but as Yugguy said they do not break so often, and it all depends from how much do you look after your car, what petrol you putting it, what parts do you buy when something goes wrong, cheap no name eaurocarparts ones, or genuine quality, do you rev the engine all the time and many other factors.

But no matter what, I would not want one, petrol is in my blood, or there is no blood long time ago.....just petrol

[HDi fun]

There's no cheap motoring to be had any more.

[Marc07]

Originally Posted by HDi fun

There's no cheap motoring to be had any more.

Motorbikes ?????
Diesel superbikes ??

[HDi fun]

Diesel engines can offer stonking performance for their size.

Most are undertuned at the factory to make way for the petrol models in the range.

But is it so efficient on a long term basis? I am not so sure. Not to say that I prefer petrol as such but I do think you should choose on merit rather than prejudice.

I'd go back to diesel immediately if I was in the market for a new £40,000 car but I'd want to dispose of it within five years.

Petrol engines are generally simpler and cheaper to maintain, and generally don't suffer from costly failures such as some dervs.

[jarrus]

Originally Posted by turbonutter69

Diesels don't always last longer than the petrol variant. It's how you maintain your car that counts not the fuel it uses.
Also I don't agree that diesels are more economical because they just aren't.

Yes and no, Yes proper maintenance is the key to long engine life but no because diesel engines have much better properties of longevity than petrol engines,

1) Revs, they don't rev as high to make there torque so there for the piston moves up and down the bore less times during it's life and so the bores and pistons and barings etc, live longer.

2) The fuel itself has a higher lubricating properties than petrol so it less abrasive on the cylinder walls and fuel pump and injectors.

A Peugeot XUD or DW should outlast a BMW M18/M19 and possibly some of the 6's if properly maintained. Hell a Merc OM60x will last forever if maintained properly

[jarrus]

Originally Posted by HDi fun

Diesel engines can offer stonking performance for their size.

Most are undertuned at the factory to make way for the petrol models in the range.

But is it so efficient on a long term basis? I am not so sure. Not to say that I prefer petrol as such but I do think you should choose on merit rather than prejudice.

I'd go back to diesel immediately if I was in the market for a new £40,000 car but I'd want to dispose of it within five years.

Petrol engines are generally simpler and cheaper to maintain, and generally don't suffer from costly failures such as some dervs.

I whole heartedly agree there chap, why do you think I stick with my old school XUD's ? Ok they aren't as refined as the newer HDI's but they are sooooo much more reliable and they are easy to fix when broken and easy to tune if you wish to do so. Diesel engines were originally designed to be simple, are modern diesels as such? I don't think so....

[Yugguy]

Originally Posted by turbonutter69

Maybe so but your service costs are more than the equivalent petrol version.
Plus if something does go wrong I'll bet it would be more to repair than the equivalent petrol version as well.

No, they're not, not at my local indy anyway. Admittedly I've never had anything diesel specific done, but cambelt, clutch and regular servicing don't appear to cost anymore than a petrol.

[jarrus]

I do think that people are being blinded by fuel economy of diesels rather than looking at the big picture, it would seem that a modern turbo diesel becomes more costly to own in the smaller engine market then the equivalent petrol, however if you go over say 2.5 litres or there abouts a modern turbo diesel makes sence especially in larger cars more so.

[HDi fun]

Originally Posted by jarrus

I do think that people are being blinded by fuel economy of diesels rather than looking at the big picture, it would seem that a modern turbo diesel becomes more costly to own in the smaller engine market then the equivalent petrol, however if you go over say 2.5 litres or there abouts a modern turbo diesel makes sence especially in larger cars more so.

hard to say, and I didn't have a bad ownership experience with the 2.2 HDi I had. However, I've been on a low budget for a couple of years and bought a petrol car for reasons of ongoing operating costs. Despite the fact that I prefer the massive torque of CR diesel engines over NA petrol engines' comparitive weedy feel.

However, there's no turbochargers to cause problems, no outrageously high pressure injection to deal with. Petrol EFI systems typically operate at around 20-25 ATM. Common rail diesels are now in excess of 2000 ATM.

So far so good. I'm growing quite fond of my BMW 528i with it's revvy little 6 cylinder, 24 valve, twin cam engine which is o so creamily smooth in its power delivery. It's actually quite good on fuel as well. Over 30mpg reliably, nearly 40mpg on a long run. Not outrageously quick (you'd outpull it in a Mondeo 2.2 ST TDCi) but it does do a good job of getting about all the same.

Servicing over the last 22,000 miles has been penny material.

But, and it's a big but, I'll be a d badge wearer again when I need to buy and can afford to buy a new car.

[davalav]

Hang on... Car enthusiasts arguing about which is better!? Surely not!

Eventually, I'll move on to petrol, but I'll always love the grunt of a diesel. they are both good, no matter how you look at it. There... sorted.