VW delays Jetta TDI diesel in U.S.

[cwerdna]

http://www.autoweek.com/apps/pbcs.dll/arti...1023/latestnews

[Sonny Jim]

The comment posted by one reader in response to the atricle was par for the course...

too bad By 2ms from USA on 11/9/2007 "Diesels are more appealing to people than ever right now with all the current focus on global warming -- their CO2 emissions are untouchable by both gasoline and gasoline hybrids cars. And, of course, their out-of-city mileage is untouchable too."

[jiepsie]

Just in case anyone's interested:
Prius emits 110 g/Km CO2
Jetta Diesel: 140 g/Km minimum.
Regardless of your favorite unit of measure, the ratio between these numbers says it all.

[Tideland Prius]

What I don't understand is that all diesel engines are turbocharged, that's why they have huge amount of torque at a low rpm. Isn't that the same as a turbocharged gas engine?

I mean if we put a 1.4 litre turbo petrol engine, it'll probably get 120hp and gobs of torque (130lbft?) and that'll make a Yaris a pocket rocket lol.

Am I missing something? Or are the diesel ppl just happy to know that we're ignoring the fact that a turbocharging a petrol engine has similar results.

[Jonnycat26]

<div class='quotetop'>QUOTE(Tideland Prius @ Nov 14 2007, 04:33 PM) [snapback]539659[/snapback]</div>

What I don't understand is that all diesel engines are turbocharged, that's why they have huge amount of torque at a low rpm. Isn't that the same as a turbocharged gas engine?
[/b]

Not at all.

Diesels make most of their power in the lower RPM ranges, both HP and Torque... that's why they 'pull' so well. Most transmissions on a diesel like car have to shift at a very Prius-like 4 or 5K RPMS.

The advantage of the diesel is the highway mileage, no doubt. When you consider the Jetta TDI and the Prius get the same mileage, and the TDI does it without any HSD benefits, you have to be impressed. When you realize the Jetta is quite a bit heavier (and safer) than the Prius, you kinda wonder if HSD is dead weight on the highway.

[Tideland Prius]

<div class='quotetop'>QUOTE(Jonnycat26 @ Nov 14 2007, 01:39 PM) [snapback]539662[/snapback]</div>

Not at all.

Diesels make most of their power in the lower RPM ranges, both HP and Torque... that's why they 'pull' so well. Most transmissions on a diesel like car have to shift at a very Prius-like 4 or 5K RPMS.

The advantage of the diesel is the highway mileage, no doubt. When you consider the Jetta TDI and the Prius get the same mileage, and the TDI does it without any HSD benefits, you have to be impressed. When you realize the Jetta is quite a bit heavier (and safer) than the Prius, you kinda wonder if HSD is dead weight on the highway.
[/b]

Yeah but what I'm saying is that isn't that the same as a turbocharged petrol engine? They have most of their torque < 2,000rpm too just like a diesel so you don't need to shift at 4-5k rpm. (usually 3-4 unless you have one of those high strung engines)

Well not quite dead weight. I mean the PSD does allow the Prius to run at a slightly lower rpm when cruising compared to a normal car + the Atkinson cycle helps a bit but yeah obviously the benefits aren't as substantial as it is in the city.

We have a 2002 4 cylinder Camry (or rather had since it was totalled in May) which weighed 1,500kg. Doing 70mph, the Camry gets about 7.0L/100km (slightly above the 6.7L/100km highway rating) while the Prius does 5.1L/100km (waay above the 4.2L/100km highway rating).

So ya 5.1L/100km (46mpg) is pretty bad for a Prius but still better than our economical Camry.

[IsrAmeriPrius]

<div class='quotetop'>QUOTE(Jonnycat26 @ Nov 14 2007, 01:39 PM) [snapback]539662[/snapback]</div>

...the Jetta is quite a bit heavier (and safer) than the Prius...[/b]

Heavier is not necessarily safer. The Prius received the highest safety rating from the EU - 5 stars. It was one of only eight cars to receive such a rating for occupant protection. I have no idea what the Jetta's is.

[Jonnycat26]

<div class='quotetop'>QUOTE(Tideland Prius @ Nov 14 2007, 04:47 PM) [snapback]539669[/snapback]</div>

Yeah but what I'm saying is that isn't that the same as a turbocharged petrol engine? They have most of their torque < 2,000rpm too just like a diesel so you don't need to shift at 4-5k rpm. (usually 3-4 unless you have one of those high strung engines)
[/b]

Not at all... diesels have a much flatter power curve that does taper off dramatically at higher RPMs. And even with a Turbo, you're just not going to get the kind of torque a diesel produces. Not to mention that the diesel needs less fuel to make the power that a gasser produces, which is kinda of the point of going diesel anyway.

[Tideland Prius]

<div class='quotetop'>QUOTE(Jonnycat26 @ Nov 14 2007, 02:45 PM) [snapback]539692[/snapback]</div>

Not at all... diesels have a much flatter power curve that does taper off dramatically at higher RPMs. And even with a Turbo, you're just not going to get the kind of torque a diesel produces. Not to mention that the diesel needs less fuel to make the power that a gasser produces, which is kinda of the point of going diesel anyway.
[/b]

True on the fuel front. But... do you mean flatter or fatter curve? (or both? lol). I'm sure a turbo petrol can produce a fatter curve (I'm thinking the old 1.8T from VW/Audi for this discussion).

[Jonnycat26]

<div class='quotetop'>QUOTE(Tideland Prius @ Nov 14 2007, 08:28 PM) [snapback]539737[/snapback]</div>

True on the fuel front. But... do you mean flatter or fatter curve? (or both? lol). I'm sure a turbo petrol can produce a fatter curve (I'm thinking the old 1.8T from VW/Audi for this discussion).
[/b]

I mean a flatter curve... And I used to own the old 1.8T, and it was a thing of beauty to drive. But the TDI had more umph off the line (altho it wasn't as fast once you got moving as the 1.8T) and it clearly used more gas than the TDI.