Petrol v diesel

[Pillock]

but you're right about the MPG on small modern petrol engines - Citroen C1 s and similar have a three cylinder engine that can get up to into the 60's.

Is that all? Seriously.... if I was choosing a pretty crappy too-small car because it was good on petrol I'd want 75mpg+My 25-mile drive to work is mostly a 50 limit and it's hard to exceed that on an 8am start with the amount of traffic sticking to 50, single carriageway all the way. In a 2.0 Golf I'm averaging 46mpg on the trip computer, and backing it up by doing the maths at the pump. To lose a cylinder, 1000cc and any practicality I'd need more than 60mpg.

[Spiny Norman]

I hate the things. Especially the modern common rail dustbin-sized turbo variety that have a power band like a 450bhp Misubishi Evo. Without the 450bhp, obviously. Unless you spend all day on a motorway at 69.5mph listening to Smooth FM, they're awful things to drive, and I really don't think the cost thing stacks up these days. There are so many potential £500+ bills just waiting to happen with a Dizzler that your 10mpg saving over an equivalent petrol car is almost certain to be wiped out if you keep it for a while.The old Puggy/Citroen ones age OK, as are the more basic VAG ones from a few years ago if you only want to spend a grand, but blowing £5k on a five year old one will lead to a world of pain.

[Pete-M]

if absolute reliability is your main criteria you can't beat Toyota (petrol or diesel) in my opinion. Personally I don't like them much, but if reliability is the be all and end all....

I'd pick a late old shape Skoda Superb. From my experience they'll happily do 80k miles in 2.5 years, abused to death, and shrug it off. Change the belt at 75k and repeat.Although, having said that, they do suffer from DMF failure.

[Jozza]

I hate the things. Especially the modern common rail dustbin-sized turbo variety that have a power band like a 450bhp Misubishi Evo. Without the 450bhp, obviously.

I think it comes down to whether or not your driving style suits a diesel. Since I spend 95% of my time driving Land Rovers with ocean-liner like torque at idle speed but bugger all power over about 2000 RPM I've got into the habit of changing up gear as quickly as possible and keeping the revs down. A modern turbodiesel with a decent VGT setup and a 6-speed gearbox or auto is perfect for driving like that and they often have huge amounts of mid-range punch when needed. The problem with the modern ones is that they've reached a sort of 'Uncanny Valley' of engine design. A good old slogging diesel like a Ford Di, Peugeout XUD or a Perkins Prima sounds like a dumper truck and makes no effort to disguise that under the bonnet there's a workmanlike lump that's all about torque and economy. A modern VAG 2.0 TDI just sounds like a petrol engine with shot tappets. Of course in the Landy world the choice is pretty much made for you- if you're buying anything under 25 years old it's pretty much always going to be a diesel, and probably a lightly-turbocharged cast-iron lump dating back to the 1950s with a BHP/litre output that would shame a Massey Ferguson.

[pogweasel]

Diesel for the "white goods" is fine, but petrol for play is still where it's at. For "ordinary driving", diesels are the way to go, I had a go in a 1.6 pez 307 the other day, utterly gutless. The diesel version may be louder and clattery but at least you get some go under your right foot, until you run out of poke. I've spent donkeys pottering about in diesel cars and vans and for day-to-day they are much better than small-capacity petrols. But come play-time, a -good- petrol car will always win out. I like my dizzle kangoo because it's cheap to run, but the second I step into the BMW I remember that driving can be fun...

[myglaren]

Daughter's Alfer GT Cloverleaf is a diesel, chosen because it is faster off the mark (0-60), has a slightly higher top speed and is much more economical than the petrol alternative.Not as economical as her Grande Punto Diesel but more fun.Doesn't sound diesely either, unlike my C5 which is unmistakably agricultural.

[dieselnutjob]

I think a lot of the diesel haters will tell you how important performance and smoothness is to them and blah blah blah and then it turns out that they have a V6 or V8 petrol car...It's not really a fair comparison.If you compare a modern 4 cylinder turbo diesel with a 4 cylinder petrol car then the diesel is likely to be quicker and use less fuel. For the petrol car to use less fuel you have to go down to some horrid tiny little engine.The only problem then is the cost of fixing a modern diesel.If you can find a good one and you can stomach maybe a couple of big repair bills over the next ten years then you could quite easily get 200,000 miles from it, by which time an equivalent 4 cyl petrol car would have long ago been scrapped. But you can't get to that kind of mileage without some bills.My 806 has eaten two DMFs, a power steering rack, several power steering pumps and a set of injectors and an intercooler, but you know what, that's not bad for 200,000 miles over ten years.My 607 has 85,000 miles and now it appears to need a track rod end, two front shock absorbers and an antiroll bar link. The particulate filter is also shagged. Again I think that's not too bad for a nine year old car at 85k either.

[seth]

I don't really have anything useful to add so I'll just leave this here.

 

[Lukas]

Of course a turbodiesel-engine will be faster and better on fuel than a petrol engine with the same amount of bhp. A modern diesel will run a very long time, but it´s more expensive to buy, more expensive to maintain and it´s by far more likely that something expensive goes wrong because compared to a n/a-petrol engine, there are so much more parts that can go wrong and will go wrong. Modern petrol engines need to be revved very hard because of the emission-ratings. They don´t have torque anymore. I would say: Modern diesels are faster and better on fuel, but expensive to run and you´d better keep a few thousands of your money if something expensive goes wrong. Modern petrol engines the same size and power are sluggish, need to be revved hard but are more reliable on the long run.

[fiatdaft]

Of course a turbodiesel-engine will be faster and better on fuel than a petrol engine with the same amount of bhp. A modern diesel will run a very long time, but it´s more expensive to buy, more expensive to maintain and it´s by far more likely that something expensive goes wrong because compared to a n/a-petrol engine, there are so much more parts that can go wrong and will go wrong. Modern petrol engines need to be revved very hard because of the emission-ratings. They don´t have torque anymore. I would say: Modern diesels are faster and better on fuel, but expensive to run and you´d better keep a few thousands of your money if something expensive goes wrong. Modern petrol engines the same size and power are sluggish, need to be revved hard but are more reliable on the long run.

sorry don't agree about diesels being faster with the same power,and modern petrols lacking in torque,my 1400 punto has 270 nm at 3k revs for example,but it depends on what you have driven i suppose.

[Spiny Norman]

I think a lot of the diesel haters will tell you how important performance and smoothness is to them and blah blah blah and then it turns out that they have a V6 or V8 petrol car...

I've yet to drive a Diseasel that compares to a modern inline 4 petrol motor for quietness and smoothness, never mind a six or a V8. Performance merely depends on the power delivery of the engine in question.

It's not really a fair comparison.If you compare a modern 4 cylinder turbo diesel with a 4 cylinder petrol car then the diesel is likely to be quicker and use less fuel. For the petrol car to use less fuel you have to go down to some horrid tiny little engine.

What I always think isn't a fair comparison is when Diseasel fans conveniently sidestep the use of high pressure fuel injection systems, huge turbochargers, intercoolers and all other expensive paraphernalia associated with dragging more than 60bhp out a 2 litre motor, when comparing them to bog standard petrol motors.If we forget the fuel consumption issue, which is hugely over emphasised and not important to anyone who does only 6-7000 miles a year, then the turbo petrol beats the turbo dizzler hands down every time.

[Arragonis]

Diesels win for me, you get used to how they drive. I find Petrol cars very weedy and lacking in oomph now, even powerful ones like a Range Rover supercharged I had a go in.DMF - A local Skoda dealer to me replaces DMFs in Octavias used as minicabs when they are new. I replaced mine which it started slipping and it cost a fortune. And it rattles a lot at tickover.For shiteness I would go for a BX, there are some about. How about a Maestro Clubman D or even better a D Turbo. I had a Turbo for 100K miles and it was ace - easy 50 mpg averaging, good speed, handling and so on.If you don't need seats in the back an old van is a decent way of getting cheap dizzle wheels ?

[Lukas]

my 1400 punto has 270 nm at 3k revs

Only with a Turbo!

[myglaren]

I've yet to drive a Diseasel that compares to a modern inline 4 petrol motor for quietness and smoothness, never mind a six or a V8. Performance merely depends on the power delivery of the engine in question.

 

What I always think isn't a fair comparison is when Diseasel fans conveniently sidestep the use of high pressure fuel injection systems, huge turbochargers, intercoolers and all other expensive paraphernalia associated with dragging more than 60bhp out a 2 litre motor, when comparing them to bog standard petrol motors.

If we forget the fuel consumption issue, which is hugely over emphasised and not important to anyone who does only 6-7000 miles a year, then the turbo petrol beats the turbo dizzler hands down every time.

Just comparing mine (2.0 HDi) with my daughter's much older Saab 2.3 (non-turbo) her engine is markedly smoother and quieter and will leave me standing.

The price to pay there is fuel consumption of course, the Saab is thirsty!

Her older, real-Saab 900 2.0 16v Turbo Aero-S was faster, quieter and the accelleration far better then the current one.

[Pete-M]

My 4.2 Rover produces 272 NM at 1000 rpm Not even the best car turbodizzlas can manage that.

[fiatdaft]

my 1400 punto has 270 nm at 3k revs

Only with a Turbo!

yup, and its not modified,try finding a new diesel without one.

[Milford Cubicle]

My 4.2 Rover produces 272 NM at 1000 rpm Not even the best car turbodizzlas can manage that.

Even the ancient VM 2.5 turbodiesel found in Rover 825s manages that at around idle.

[dieselnutjob]

The first turbo diesel sold in Europe was the Peugeot 604 TD in 1979. Even that had near 200Nm which is why they had to change from the BA7 (as used on other diesels) to the BA10 transmission.

[garethj]

but you're right about the MPG on small modern petrol engines - Citroen C1 s and similar have a three cylinder engine that can get up to into the 60's.

Is that all? Seriously.... if I was choosing a pretty crappy too-small car because it was good on petrol I'd want 75mpg+My 25-mile drive to work is mostly a 50 limit and it's hard to exceed that on an 8am start with the amount of traffic sticking to 50, single carriageway all the way. In a 2.0 Golf I'm averaging 46mpg on the trip computer, and backing it up by doing the maths at the pump. To lose a cylinder, 1000cc and any practicality I'd need more than 60mpg.

A bloke in work here has a newish Micra diesel and it does 70-72mpg.But I'm sure a 1 litre Citroen AX would do 60mpg as long as you didn't load it up?

[dieselnutjob]

I can't think of any advantage of a 1.0 petrol over a 1.5 turbo diesel though.

[M'coli]

I can't think of any advantage of a 1.0 petrol over a 1.5 turbo diesel though.

Weight. That's about it.

[Arragonis]

But I'm sure a 1 litre Citroen AX would do 60mpg as long as you didn't load it up?

My old Nova 1.5TD (from about the same time frame as the AX) would do 65-70 MPG wihout trying and played in the fast lane of the M62 outrunning BMWs up the hills every day. And I'm fat

 

I can't think of any advantage of a 1.0 petrol over a 1.5 turbo diesel though.

Compact size, lightness and cheapness are the main advantages of the smaller petrol engine to a diesel, all of these go to make smaller cars (Aygo, 107 etc.) cheaper to make and buy.

 

They did shove in the non-turbo HDi engine into the Aygo/107/C1 as there was not enough room for the turbo and cooller gubbins. If they had then that would have been a 100 mph/80+ MPG car I'm sure. Instead it was very sluggish and didn't sell well at all. I think only the C1 has it now.

 

You could also argue noise is an advantage of petrol engines but most of the noise in a modern diesel is from the fuel pump. With common rail etc. the noise difference is coming down all the time.

[r.welfare]

Toyota D4-Ds seem to suffer from fuel pump failure. I'm not sure if there's any modern diesel that seems immune from this, or DMF failure as noted. However, some makes are more susceptible than others, and regular servicing (certainly more frequently than the 18-20k intervals that are prevalent these days) probably helps.Having switched recently from a 1.9TD Peugeot 405 to a 2-litre petrol Toyota Avensis, I find that I'm getting 42mpg (proper brim-to-brim calculations) from the Toyota compared to 47mpg from the Pug, under comparable conditions (70% 75mph motorway cruising, 30% A/B road work).I drove a Saab 9-3 1.9TiD (the eight valve, 120bhp version) for 11 months from new and did 25k in it. Nothing went wrong, but the 1.9TiD (also used in Vauxhalls and Alfas) doesn't have a very good reputation, although eight-valve units (120bhp) seem to be better than the 16-valve 150bhp unit. This averaged 48mpg under the same conditions as above. There was absolutely no power at very low revs when off-boost, totally unlike the Peugeot, which was virtually impossible to stall. Dervs are GR8 4 lazy driving, but some are better than others.

[Pete-M]

I can't think of any advantage of a 1.0 petrol over a 1.5 turbo diesel though.

Weight. That's about it.

Weight, smoothness, quietness, loveliness, ability to rev. Petrol wins all of those.

[dollywobbler]

Loveliness from a 1 litre four pot? Methinks not!I adore the simplicity of the BX's engine. No ignition to worry about, daft mpg and not embarassingly slow (though much slower than modern TDs!)

[Pete-M]

Loveliness from a 1 litre four pot? Methinks not!

Fireblade engines aren't diesel

[Milford Cubicle]

Going fast is the mark of a car enthusiast.

[pogweasel]

A bloke in work here has a newish Micra diesel and it does 70-72mpg.

No, it doesn't.That's what the salesman/brochure told him. Those 1.5DCi engines are simply nowhere near as efficient as the figures would have you believe.

[dollywobbler]

Pah! I won't have anything to do with this fast malarky.I presume a Fireblade is some sort of bike thing? I was thinking Citroen AX...

[Milford Cubicle]

A bloke in work here has a newish Micra diesel and it does 70-72mpg.

No, it doesn't.That's what the salesman/brochure told him. Those 1.5DCi engines are simply nowhere near as efficient as the figures would have you believe.

If you drive everywhere in a thrifty manner, diesels can be mega efficient, but if you drive everywhere spooling the turbo up all the time they are merely a bit more efficient than a petrol.