40 mpg Prius vs 50 mpg European Diesel cars

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?

 

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

 

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.

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.)

 

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

 

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

 

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).

 

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.

 

Gasoline is more versatile.

 

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.

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.

 

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.

 

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.

 

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

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.

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

 

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

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

Lynn

 

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

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.

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

 

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..

 

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.

 

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

 

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.
--

 

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?
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