40 mpg Prius vs 50 mpg European Diesel cars

[perfb]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) with claims of 50 mpg mileage according to some owners I spoke to. They were pretty comfortable cars, too, just not as big as in the USA, though not tiny by any means, quite comparable to the Prius in size.

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, and that with a turbo diesel you can get decent performance AND high mpg, why the heck are the majority of cars in the USA still gasoline?

Is there some other factor that overrides the inherent efficiency of diesel? e.g. pollution? Is that really it? Or, is it just market inertia and historically low fuel prices relative to Europe?

 

[Peter Chant]

Is there some other factor that overrides the inherent efficiency of diesel? e.g. pollution? Is that really it? Or, is it just market inertia and historically low fuel prices relative to Europe?

I suspect fuel prices. I had a V6 mustang in the us a few years ago as a hire car. I did about 1200 miles in a week in it. Due to the differences in fuel prices it was much cheaper than running my 306 diesel back home. Even when I filled up twice in one day I did not spend much on fuel. Actually it was not two complete tanks, just that I did not want to run out of fuel anywhere embarrassing, like in a desert.

I don't understand Priuses, as a technology demonstrator they are interesting but from what I have seen they are not as efficient as a diesel.

Pete

 

[Andrew Stephenson]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) [...]

In Europe we have been developing and using diesels seriously in cars far longer than the US has, AFAIK. Private perceptions and legislation played their part, as did the clunky performance of designs back when attitudes were being set in stone. Add to that give-away prices of petrol in the US and it's not hard to realise why diesel became the Sooty Sheep of the fuels-family there.

For many years, in the UK diesel was not taxed as hard as petrol
-- not sure what today's situation is, as I don't run a diesel and anyhow prices (and taxes) are wandering all over the place. The famous London black taxis went diesel around when Adam was a lad, though the pong of diesel and vibration (coupled with urban taxi driving style) could be stomach-churners for passengers.

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, [...]

That figure is likely to depend on petrol engine type. You may be thinking of the commonplace Otto; but (and I mention it purely as you troubled to mention the Prius in your Subject and posting list) the Atkinson is more efficient than the Otto, especially if operated at/near constant speed, and we surely have not heard the last of oddities like the Stirling. Add modern control systems. IOW, study the whole vehicle package when evaluating efficiency.

Previous discussions have wondered whether future hybrid cars may incorporate diesels, as do some buses currently being trialled in the UK. (NB: Google is your friend.)

 

[Michael Pardee]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) with claims of 50 mpg mileage according to some owners I spoke to. They were pretty comfortable cars, too, just not as big as in the USA, though not tiny by any means, quite comparable to the Prius in size.

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, and that with a turbo diesel you can get decent performance AND high mpg, why the heck are the majority of cars in the USA still gasoline?

Is there some other factor that overrides the inherent efficiency of diesel? e.g. pollution? Is that really it? Or, is it just market inertia and historically low fuel prices relative to Europe?

Disclaimer - my experience with diesels is limited to my TDi work truck.

Diesels are still cantankerous - cold starts are problematic; they still clatter like something's wrong, especially when cold; the diesel guys who gave me basic instruction warned me to take it easy on the engine until it warmed up / quieted down. Cars like Mercedes have quiet interiors as a result of insulation, but outside they still clatter (so my former Euro-car mechanic partner tells me.) Smoke is a normal part of start-up and warm-up and smell is a normal part of operation. I canna change the laws of physics.

Turbo diesels are plenty powerful once the turbo gets spun up, but until then I wish I had four feet so I could hold the accelerator to the floor with one, feather the clutch with a second, and do the Fred Flintstone thing with the other two. You haven't experienced turbo lag until you've waited for 20 psi boost to appear. (I understand VW's variable vane turbo reduces that quite a bit, but one still has to choose one's gap in traffic carefully.) Hybrids excel in off-the-line performance. A TDi hybrid, when the technical details are worked out, would make a dynamite power train. Even an electrically boosted turbocharger would be an improvement.

Every diesel pump handle I've picked up is a smelly, oily thing. Gasoline evaporates, diesel accumulates. I always wear gloves while fueling.

Diesels give great economy on the highway, but scarcely better than conventional gasoline engines in town. Hybrids walk all over them for in-town economy.

Mike

 

[twfsa]

What you save in fuel mileage you loose when it breaks, and parts are needed( more expensive) also fuel filters and maintenance cost are another looser, Diesel fuel is more expensive than gasoline in today's market, in the winter you need blended fuel or worse #1 that's probably going to cost $3.75 a gal this winter, or expensive additives that keep the fuel from gelling.I have owned 2 diesel and there great for mileage but when it breaks no matter what it is, it cost more!

Tom

 

[Ken (archive)]

This is a drivel post. Diesel is more energy-intensive than petrol. This is the sole reason diesels show a mileage advantage.

On my farm I have both diesel and petrol vehicles and the diesels always put put more work per litre than the petrols.

To introduce the petrol/diesel energy differential into the greenhouse debate is a red-herring. Whenever we dig up fuel and release it into the atmosphere we are bringing the day when Venice, London, Sydney and Tuvalu disappear below the waves closer.

The fractioning process which separates diesel from petrol uses energy
- probably more than than the energy-advantage of diesel compared with petrol.

The only fundamental advantage of diesel may be that its engines last longer (because diesel, unlike petrol, is a lubricant - I have never seen any research results on this but I have a geriatric Ford 2000 tractor which will probably outlast me).

 

[Keith Willcocks]

<snip)
Diesels are still cantankerous - cold starts are problematic; they still clatter like something's wrong, especially when cold; the diesel guys who gave me basic instruction warned me to take it easy on the engine until it warmed up / quieted down.

This was true of Turbo Diesels but I have found that the modern common rail diesel engine (of which I have Peugeots HDI model in the 406 that I had new in 1999) starts better than any petrol engine I have used and is far less noisy than its predecessors. Also, unlike petrol engines, there is no drop off in performance before the engine warms up, it starts and is ready to give full acceleration straight away.

Turbo diesels are plenty powerful once the turbo gets spun up, but until then I wish I had four feet so I could hold the accelerator to the floor with one, feather the clutch with a second, and do the Fred Flintstone thing with the other two. You haven't experienced turbo lag until you've waited for 20 psi boost to appear.

Again, IME, the HDI engine seems not to suffer from any lag and is more akin to driving a petrol engined car when it comes to pull away and acceleration. And for interests sake my car averages 46mpg.

 

[mark_digital©]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) with claims of 50 mpg mileage according to some owners I spoke to. They were pretty comfortable cars, too, just not as big as in the USA, though not tiny by any means, quite comparable to the Prius in size.

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, and that with a turbo diesel you can get decent performance AND high mpg, why the heck are the majority of cars in the USA still gasoline?

Gasoline is more versatile.

 

[Brian]

To introduce the petrol/diesel energy differential into the greenhouse debate is a red-herring. Whenever we dig up fuel and release it into the atmosphere we are bringing the day when Venice, London, Sydney and Tuvalu disappear below the waves closer.

And New Orleans but that is perhaps another issue.

Of course, diesels also can run on bio-fuel, which is now readily available, though not in large enough quantities.

The fractioning process which separates diesel from petrol uses energy
- probably more than than the energy-advantage of diesel compared with petrol.

The only fundamental advantage of diesel may be that its engines last longer (because diesel, unlike petrol, is a lubricant - I have never seen any research results on this but I have a geriatric Ford 2000 tractor which will probably outlast me).

Fundamentally, they also push out less greenhouse gasses than petrol engines. The new engines, with exhaust filters are cleaner than any other IC engine currently.

 

[Michael Pardee]

This was true of Turbo Diesels but I have found that the modern common rail diesel engine (of which I have Peugeots HDI model in the 406 that I had new in 1999) starts better than any petrol engine I have used and is far less noisy than its predecessors. Also, unlike petrol engines, there is no drop off in performance before the engine warms up, it starts and is ready to give full acceleration straight away.

Again, IME, the HDI engine seems not to suffer from any lag and is more akin to driving a petrol engined car when it comes to pull away and acceleration. And for interests sake my car averages 46mpg.

I've heard "yes" and "no" that Europe has more refined diesels (a Swedish friend who visits family every year says "no"); I presume the common rail engines are the ones they are talking about. I'll have to study those more. Do you know if they are available in any US cars?

Mike
(who agrees about the laughter!)

 

[Keith Willcocks]

I've heard "yes" and "no" that Europe has more refined diesels (a Swedish friend who visits family every year says "no"); I presume the common rail engines are the ones they are talking about. I'll have to study those more. Do you know if they are available in any US cars?

Mike
(who agrees about the laughter!)

I have no idea whether they are available in the US but I would be surprised if they weren't. I am in England and common rail are the norm over here now. Different companies have different names for their version, Peugeot is HDI but I have seen many others, much like the different names given to automatic gearbox systems. My cousin who was over from the States was well impressed with my Peugeot 406.

I am no expert but as I understand it the older diesels had a pump looking like a distributor with a pipe to each injector and it pumped a shot of diesel into each cylinder at the appropriate moment being controlled mechanically. The common rail has one pipe along the side of the engine (the common rail) which has a pipe to each injector and the whole system is under continuous high pressure. The injectors are controlled electronically by the ECU which instructs them when to inject fuel and how much. Obviously there is much more to it but that is all I know. Suffice it to say that there is a world of difference between driving the two types. I believe you even get Jaguars now with common rail diesel engines.

Glad you like my motto, its works well in this day and age.

 

[Michelle Steiner]

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, and that with a turbo diesel you can get decent performance AND high mpg, why the heck are the majority of cars in the USA still gasoline?

Diesel pollutes more than gasoline does; once sulphur is removed from Diesel fuel, that might change.

Further, in many parts of the US, Diesel is more expensive than regular unleaded gasoline--and is often more expensive than hi-test unleaded. Especially in the winter, when Diesel is used for heating homes in the Northeast part of the country.

But where did you get that 40 MPG figure for the Prius? Most of us get in the neighborhood of 50 MPG, and some get 60 MPG.

 

[Chris Dugan]

Diesel pollutes more than gasoline does; once sulphur is removed from

Diesel fuel, that might change.

In Europe and here in the UK we already have low Sulphur Diesel, Catalysts in the exhausts clean up particulates so that today the average modern (i.e. less than 5 years old) HDi/DCi/TDCi etc engine is not only more fuel efficient but also cleaner in particulates and CO emissions than an equivalent powered Petrol engine.

Further, in many parts of the US, Diesel is more expensive than regular unleaded gasoline--and is often more expensive than hi-test unleaded. Especially in the winter, when Diesel is used for heating homes in the Northeast part of the country.

Don't get that problem here because of economies of scale, if you used more diesel it would be cheaper to buy and more readily available.

Chris

 

[Lynn McGuire]

What you save in fuel mileage you loose when it breaks, and parts are needed( more expensive) also fuel filters and maintenance

cost are another looser, Diesel fuel is more expensive than gasoline in today's market, in the winter you need blended fuel or worse #1 that's probably going to cost $3.75 a gal this winter, or expensive additives that keep the fuel from gelling.I have owned 2 diesel and there great for mileage but when it breaks no matter what it is, it cost more!

Here in Houston, Texas, gasoline is $2.99 and diesel $2.79.

Lynn

 

[Lynn McGuire]

This is a drivel post. Diesel is more energy-intensive than petrol.

This is the sole reason diesels show a mileage advantage.

Wrong.

1. Diesels vary their air to fuel ratio. Under partial loads, diesel air to fuel ratio can exceed 100 to one, Gasoline air to fuel ratio is 14.7 to 1.

2. Diesels use very high compression. Engine efficiency is a function of compression ratio.

3. Diesel has about 11% more efficiency than gasoline on a volume basis.

To introduce the petrol/diesel energy differential into the greenhouse debate is a red-herring. Whenever we dig up fuel and release it into the atmosphere we are bringing the day when Venice, London, Sydney and Tuvalu disappear below the waves closer.

That is a hypothesis, not a fact. However, using a vehicle that is more efficient than another just makes sense if you believe this.

Lnyy

 

[Chris (2)]

Here in Houston, Texas, gasoline is $2.99 and diesel $2.79.

Lynn

thats it i am going to ship alot of diesel over to the u.k for my self. as it is cheaper.we are paying 98.9 lt which is well over the price.and why is it one tescos can charge 98.9 and the other one which is only
1.5 miles away can charge 99.9. if any body knows the reply..

 

[someone]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) with claims of 50 mpg mileage according to some owners I spoke to. They were pretty comfortable cars, too, just not as big as in the USA, though not tiny by any means, quite comparable to the Prius in size.

The European gallon is also 20% bigger. So 40mpg on a US gallon vs 50mpg on an Imperial gallon isn't that big a difference.

 

[Brian]

what it is, it cost more!

Here in Houston, Texas, gasoline is $2.99 and diesel $2.79.

Lynn

Well, here in the UK it is more like $6.60 per US Gallon.

 

[The I'm done being benevolent dbu.]

I noticed in Europe that diesels and turbo diesels are very common (eg Peugeot) with claims of 50 mpg mileage according to some owners I spoke to. They were pretty comfortable cars, too, just not as big as in the USA, though not tiny by any means, quite comparable to the Prius in size.

So, given the fact that a diesel engine is ~15% more efficient, mpg-wise, for the same horsepower than a gasoline engine, and that with a turbo diesel you can get decent performance AND high mpg, why the heck are the majority of cars in the USA still gasoline?

Is there some other factor that overrides the inherent efficiency of diesel? e.g. pollution? Is that really it? Or, is it just market inertia and historically low fuel prices relative to Europe?

The VW diesel Rabbit was able to approach 50 Mpg a number of years ago...

Yep, I think it was the smell. Diesel is also easier to refine.

 

[The I'm done being benevolent dbu.]

Diesel pollutes more than gasoline does; once sulphur is removed from Diesel fuel, that might change.

Further, in many parts of the US, Diesel is more expensive than regular unleaded gasoline--and is often more expensive than hi-test unleaded. Especially in the winter, when Diesel is used for heating homes in the Northeast part of the country.

But where did you get that 40 MPG figure for the Prius? Most of us get in the neighborhood of 50 MPG, and some get 60 MPG.

Didn't use to be. In years past diesel was much cheaper than gas. I don't know why it's higher now, perhaps because of environmental crap.

Tell me is the 50 and 60 MPG figure city driving or on trips. I'm told on trips the milage goes down because the gas engine is running more. In city driving the electric is running more. Is this true?