Bogleheads

[Bounca]

Anyone have any experience with diesel cars? I'm particularly interested in the VW Jettta TDI which gets phenomenal gas mileage. Some specific questions…..

Is diesel always a bit cheaper than regular gas? I don't keep an eye open as to prices for diesel since it's a non issue for my past vehicles.
What pros and cons are there?
Is VW track record good, I kind of think there history is a bit poor?

When the discussion comes to fuel efficient cars the talk is always about the Prius, Corrola, Civic, etc. (all of which I've researched) and the Jetta diesel TDI seems to get a back seat (< nice pun).

Thanks for everyone’s input.

[rwwoods]

A web search on diesel will turn up a lot of information. Here is what I learned:
1. diesel cost more than gasoline at the moment due to the high worldwide demand
2. diesel has more energy per gallon than gasoline which is what provides the high mileage and lower cost/mile
3. the new diesel engines are designed to use ultra-low sulphur fuel and have low emissions by using new electronic controls the reliability of which are unknown at this time
4. the emission levels are still higher than California limits
5. cold weather starting is still a problem - a block heater or garage is needed in the northern climes
6. engines are still noiser
_________________
All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Arthur Schopenhauer, German philosopher (1788 - 1860)

[Valuethinker]

[Valuethinker]

[gkaplan]

Volkswagens are notoriously unreliable, at least according to Consumer Reports.
_________________
Gordon

[craigr]

I have two diesels (Dodge w/Cummins engine and Mercedes). They are both very reliable vehicles. Don't know much about VW. I had a friend who owned one and it seemed to have a lot of problems.

Here are some reasons why I like diesels:

Diesel is usually cheaper but is now pricier than premium in my area. This will eventually revert I'm sure.

Diesels are cleaner than gas in some respects. Where they usually get pinged is the higher particulate emissions and a few other things.

Diesel engines don't have an ignition system which is one less series of components to break (no spark plugs, ignition coil, cables, distributor, etc.).

Diesel engines are built heavier to deal with the high compression needed for ignition. Because of this they tend to last a really long time.

My Mercedes can get almost 35MPG on the highway and about 28MPG around town. Not too shabby for a full size four door sedan. My truck gets 20-22 MPG on the highway which is also quite good for a full size 4x4 truck.

Diesels can run on fuel alternatives such as bio-diesel. They can also run on cooking oil or other raw oil in an emergency for short stretches.

Diesels produce good low-end torque which is what makes them powerful. Gasoline engines need to produce higher RPMS to get the same horsepower. Because of the lower general RPM diesels can work less and put less strain on the engine which helps engine life.

[Valuethinker]

[bearcat98]

[PaPaw]

Only thing I would add from my limited perspective is:

Diesel exhaust and spilled diesel fuel tends to "stink" more than their gasoline counterparts. Especially important if you happen to get fuel on your shoes at the filling station and track it into your wife's just cleaned house!

Make sure to calculate your breakeven point vs. gasoline with fuel economy, fuel price, car purchase price, and maintenance considerations. Might be a surprise or two there.

Diesel fuel availability seems to be much more limited in my area than gasoline, and as others have said, diesel is costing more than premium gasoline. Perhaps the market has recognized diesel contains about 10% more BTUs per gallon than gasoline and is pricing it accordingly.

Be sure the shop where you plan to go for service has an excellent ethical reputation and is experienced with the type of technology you purchase, e.g. diesel engines, electronics, etc. That is at least as important as buying a reliable vehicle to start with (i.e. per Consumer Reports) in my opinion.

[heyyou]

When I had the same questions recently, one mechanic friend said the VW diesels had mediocre longevity due to head problems from lack of strength caused by shaving too much weight off of the engine. That could be improved by now on newer models. I bought a used Toyota instead. On small, hobby farm tractors where weight is an advantage, those Japanese diesels run forever. My Yanmar is 30 years old.

I agree with VT that a Cummins truck engine, a Mercedes engine, and a little VW engine may not have much in common. Do investigate the added initial cost of a diesel engine.

When Izusu was making diesel mini-pickup trucks, a friend's truck needed new injectors. The used truck was worth the same price as the repair job, $2000, and that was about 1990. A Mercedes may have the same high cost of repairs, when repairs are finally needed.

[jeffyscott]

It seems to me that for the last few years diesel has been cheaper than gasoline in the summer and more expensive in the winter. I assume this is due fuel oil use for heating increasing demand in winter.

Right now in my area diesel is about $4.05, which is about 20% more than regular gas.

I believe in the lastest consumer reports the current version of the Jetta has achieved average reliability. I tend to think the actual differences are not all that great between most cars. We bought a gasoline Jetta a few years ago and one thing I looked into, but did not buy, was the cost of an extended warranty from my credit union for it and a comparable "reliable" vehicle. A warranty on a Jetta was more than for an Accord, but only by about $500 for 100,000 mile warranty. With what amounts to a difference of $50 per year in expected repair costs for us, my wife chose to buy the car she liked.
_________________
Jeffy

press on, regardless - John C. Bogle

[craigr]

[tibbitts]

I'm not sure we can compare the diesels of even a year ago with what's out there today. There are conflicting reports on the impact of the lsd and new emissions systems on fuel mileage. I have only secondhand information, but for example, the mercedes-powered sprinter vans have undergone a change of engine design in the past year, required to meet the new emission requirements, and initial reports seem to be that the new design is not competitive with the old design in mileage. But mileage with diesels sometimes improves significantly after several tens of thousands of miles, so it's possible that early reports are misleading. There seem to be mixed reports on mileage from the new 6.7L cummins, which has replaced the long-standard 5.9L cummins in dodge trucks.

For those of us who park with our tailpipes pointed at a white painted wall 12" away, I suspect the decision of gas or diesel may be obvious, even with modern diesel emission controls. It's really amazing how clean my wall stays with even a relatively ancient (00 model year) gas engine, compared to what it looked like after being blasted by gas engines from the '60s - '80s.

Paul

[craigr]

[Captb]

I owned a Jetta Diesel back in 1980 and got great MPG - 50s with my five speed stick. Much has changed in diesel technology especially with the addition of the turbo - which makes the car reasonably peppy. The new Jetta's are also quieter.

Having said all that - I would not buy a VW diesel at this time for three reasons:
1. Diesel fuel sells in my area at $4 per gal. vs $3.20 for gas. This 20% premium for diesel does not make purchasing a diesel cost effective at this time.
2. I had engine problems with my Jetta and VW's overall reliability is poor!
3. If you must have a diesel - can you wait for the 2009 Honda Accord. They are planning on offering a diesel and it should be a great improvement on the VWs.

[Valuethinker]

[Valuethinker]

[stratton]

[Bounca]

[jeffyscott]

[rvander1]

Hi,
--A slightly different, but related matter--
In 2004, I took my family to Italy for a week (rented a house on the Sorentine Peninsula, just south of Naples. I rented a diesel Fiat for the week and drove it all over the very hilly terrain. It was, IMO quiet (you couldn't tell it was a diesel when listening to it idle), had great pickup (don't know if it was a turbo), and was really a ball to drive-- didn't feel like driving a tank. It also got great mileage. If you didn't know otherwise (we all agreed) you would think it had a gas engine.
I've been seriously thinking about getting a similar small diesel car here in the US- but I don't know if it is even available!
There are clearly knowledgeable people on this thread so:
Is there such a small, peppy, diesel car available in the US, that is reliable?
Why no Fiats (there are Alfas (made by fiat).
Very informative thread--

[jeffyscott]

[Valuethinker]

[LedMizer]

The OP may also want to check their state DMV regs for registering a diesel passenger car in their state.

New York has restrictions about registering these car because "they cause so much pollution."

[yakers]

Jeep currently sells a Grand Cherokee with the same Blutech engine Mercedes uses in its vehicles and costs a lot less than MB. I have a 2006 Jeep Liberty diesel (they only were sold in the US in 2005/06), it has a 2.8 turbo engine. I have not had any problems with it. I just love driving it, it is nothing like the 1966 Mercedes 200D I once owned although I also loved that car. It does not get the same great mileage, I get 20 to 22 around town, my best highway milage was 27 MPG but I sometimes tow a travel trailer and I get 18/19 while towing. For me this is a compelling vehicle as the diesel gets much better milage than the gas engine and the torque is very effective for towing. Maybe a diesel is a better combination in a SUV than a car.

[jeffyscott]

[yesosaka]

[Valuethinker]

[Valuethinker]

[tommy_gunn]

In CA diesel is much more expensive than regular gas, and more then premium, over $4 gal

I have never owned a VW, but know many who have, and they were all junk after a few years, expensive to repair. German cars require expensive parts.
_________________
"I love competition. And I want to win." R. Murdoch

[Buffett_wannabe]

Great discussion. Few additional points:

1. Diesel prices in North America are cyclic with the peak coming in winter since home heating oil is almost identical to diesel and they compete for refinery space. Both diesel and gasoline prices are artificially high in the USA because refinery capacity is constrained (thanks to environmental and NIMBY permitting headaches among other reasons, not one new refinery for 30+ years). Neither this nor the costs of transitioning to ULSD diesel adequately explains this spring's price spike, though.

2. Federal excise taxes are 6c per gallon higher on (highway use) diesel than gasoline. This was AFAIK intended to tax heavy trucks for the exponentially greater wear they inflict on highways vs. automobiles. Does anyone have figures how European governments tax diesel vis-a-vis gasoline? (A state-by-state breakdown is available from the American Petroleum Institute.

3. The greater efficiency at idle mentioned by Valuethinker is partly explained by the lower throttling losses of a diesel. Gasoline engines typically have a butterfly throttle valve in the intake system, while diesels do not (combustion takes place in excess air always so diesels are throttled by controlling the fuel injected). Working against the manifold vacuum downstream of the throttle is a "fixed cost" for the gasoline engine not shared by a diesel. It will be interesting to see if modern throttleless gasoline engines e.g. BMW's Valvetronic can come closer to matching diesels in this respect.

4. (testimonial) A few years ago when Hurricane Rita prompted a mass evacuation of Houston, my in-laws chose to make the escape in my father-in-law's old GMC diesel 3/4 ton (a 6.5L non-turbo) towing their 6600-lb travel trailer. I remember because I had to help Dad back that monster into our driveway! Despite the huge gridlock (2 days to go 150 miles), the truck didn't use more fuel than a normal 2-hour drive would have consumed, and that was after they ran the engine all night so they could have A/C to sleep. Similar experience reported by friends who made the trip in an ancient Jetta diesel. Considering the number of motorists who burned up a full tank of gasoline and got stranded, I was deeply impressed. If I lived in hurricane country or someplace else where a mass evacuation was likely, I would definitely consider keeping at least one diesel vehicle as my "bug-out car".

Regards,
Craig B.

[jeffyscott]

[Valuethinker]

[craigr]

[jeffyscott]

What is any more misleading about figures such as 10, 20, 50, 100 mpg vs. 10, 5, 2, and 1 gallons per 100 miles?
_________________
Jeffy

press on, regardless - John C. Bogle

[Valuethinker]

[Valuethinker]

[craigr]

[jeffyscott]