What Would It Take for YOU to buy a diesel car?

lemmer

No, I am saying you cherry picked a couple of points of anecdotal evidence.

A better choice might be something like fuelly. Based on 49 Touareg TDIs, owners seem to be averaging somewhere around 23-24 MPG. 49 responses isn't conclusive, but it is far better than you picking one single anonymous person.

That kind of MPG is outstanding for a large SUV. Why tarnish that accomplishment by throwing out wild, easily refutable numbers?

ruking1

Those 49 responses are also anonymous and inconclusive and anecdotal.

busiris

If someone posted the results of an Edmunds or R&T or some other big name long term test, they'd have a leg to stand on. If someone relied upon the EPA estimates, they'd have a leg to stand on. If someone posted the combined results of thousands of users, they'd have a leg to stand on.

But just posting anecdotal evidence of one or two anonymous people is almost worthless.

I agree completely.

I have an advanced degree in statistical analysis, and I am always entertained when people attempt to use numbers to justify their beliefs, instead of letting the numbers speak for themselves.

Off hand, one of the few times I can see only 2 samples being significant is your birth data and the date you die, and even then, its only significant to you.

As an old stat instructer repeatedly told me back in college... "one or two points on a graph don't signify a trend".

ruking1

I agree, the numbers always speak for themselves.

But then based on that, it isn't like you are going to buy 10,000 Acura MDX's or 5,000 TDI's. Like your BD, etc. you are only probably going to buy one and concerned about that ONE, AND what you buy is going to only be significant to YOU.

lemmer

Agreed.

ateixeira

A sample of 49 is far, far more significant than a sample of 2.

That single person who reported 32mpg is an outlier - it might even make sense to discard the highest and lowest reported numbers.

I still say it's foolish to assume you will average 30mpg in any 5000+ lb SUV. I'd be happy with 25.

lemmer

The Golf TDI ends up right around 40 MPG. The Prius reports are a little more erratic but look to be around 45 MPG.

This indicates the Golf typically does better than the EPA estimates and the Prius does worse.

ruking1

I am assuming nothing. It is easy to get close to 25 mpg with the MDX. We normally get 23 mpg keeping it under 85 mph. That is on the upgrade. So if you say you can't get 25 mpg or so, I would say you are hammering it way past 85 mph. In which case or any case, I can not control how YOU drive.

lemmer

A friend of mine had a Lexus CT200h as a loaner car today. I actually kind of like it. The front felt big but my head rubbed the headliner. And the back seat is pretty small. I fit way better in my Mom's Golf TDI, which is of course, far less expensive.

lemmer

Do you only drive downhill?

ruking1

If I got 40 mpg with my 03 Jetta TDI (same engine but heavier) I would think something wrong with the car. But yes, I would pick no bone with someone who does.

ateixeira

He started at Pikes Peak and measured at the bottom. Then swap and drive the MDX up the hill.

Jokes aside, the advantages of diesels are clear without cherry picking data points.

On that EPA site, one outlier reported 32mpg...maybe that's the guy who lives at the top of Pikes Peak.

ruking1

I think you have been ignoring my posts, which is fine. 48 mpg up grade (keep under 90 mph(destination 6,700 ft from sea level ) and 52/53 down grade (slower because of LLC'ers).

busiris

But then based on that, it isn't like you are going to buy 10,000 Acura MDX's or 5,000 TDI's. Like your BD, etc. you are only probably going to buy one and concerned about that ONE, AND what you buy is going to only be significant to YOU.

Of course, the item YOU purchase is the most significant one to YOU, but its not when you are attempting to project the future outcome of an as-yet unmade purchase.

If I am comparing 2 similar products, and one has a sample of 5 owners with a FE of 20 mpg, and the other has 500 owners reporting a FE of 25, I'm going to have a much higher comfort level that the second item will approach that same FE IF I purchase it.

The more samples one has, the better the chance of approximating reality.

While 1 or 2 samples of dropping a 8 lb bowling ball on your foot many be sufficient to convince you it will hurt, using the same bowling ball at your local bowling lanes for 1 or 2 frames may not be enough samples to let you know that particular weight ball is the best option for you.... when it comes to bowling. You may bowl much more successfully with a lighter or heavier ball.

lemmer

I've read your posts. I commend you on your hyper-miling abilities. But that doesn't mean they are indicitive of an average experience.

It is just disingenuous to say that you get 50 mpg and compare that to an average person in a Prius getting 45 mpg. If you had a Prius, it would stand to reason that your abilities would allow you a 25% increase in mpg over the average person. So, in a Prius you should likely see about 56 mpg.

lemmer

You are speaking my language, Busiris.

ruking1

Along the same lines, diesels in the passenger vehicle fleet are less than 5%. So there is much less a population to draw upon. Indeed when I bought the 2003 TDI there was app 9,000 units. So the explanation is sophomoric.

ateixeira

You can actually statistically calculate using confidence intervals. You need a large sample, but you can say, mathematically, that you would have 90% or 95% confidence in being able to repeat a result if you have a large enough sample to base it on.

A sample of two would make my statistics teacher laugh pretty hard.

qbrozen

hmmm... I have to disagree. It is ahead by almost a full sec by 60, but then only .6 at the 1/4 mile mark. Seems to me the TDI is catching up in the higher gears. And, mind you, this is the same on the figure 8. The MDX jumps ahead nearly a full sec on that first standing start straight ... then the TDI pulls it in by a third of a sec by the end of the run. So it technically gained on it. I read that as meaning they would be neck and neck after 2 more laps.

In any case, a half sec or even a full sec .... when comparing mid-sized SUVs, mind you... is nothing. I'd say they are quite comparable no matter who is ahead.

ruking1

..."I've read your posts. I commend you on your hyper-miling abilities. But that doesn't mean they are indicitive of an average experience. "...

I am far from a so called hyper miler. Nor have I ever said that it was indicative OF an average experience !!! Indeed it was I that said that even I realize getting 38-42 mpg on a GASSER (2004 Honda Civic) is high on the bell shaped curve. It is not a leap to say that of diesels also. However one KEY issue is, I am in tune with each's characteristics, i.e., power curves and drive them accordingly.

lemmer

OK, I guess that just leaves EPA numbers to rely on for comparison. I can live with that.

gagrice

The average Joe is not going to get over 30mpg in a 5062 lb SUV, no matter what engine you put it in.

You all can believe what you want. But the Touareg TDI sold in the UK is rated at 40.4 MPG combined. Now if my conversion is correct. That would be 33.64 MPG US. That is the detuned version of the TDI sold here. So they are out there. Just not sold here in the land of fruits, nuts and flakes.

http://www.carpages.co.uk/guide/volkswagen/volkswagen-touareg-se-3.0-v6-tdi-204p- s.asp

If you want the fast version of the Touareg you can get a V8 TDI that does 0-62 MPH in 5.8 seconds. And get you almost 32 MPG on the highway. Face it we get sold the dregs. You can have your foo foo MDX, I would not waste room in my garage with one.

http://www.carpages.co.uk/guide/volkswagen/volkswagen-touareg-altitude-4.2-v8-td- i.asp

ruking1

So would 49.

ruking1

Actually mine has been pretty easy to live with EPA of 42 to 49. and for 176,000 miles. I get 50 mpg, whats the BIG deal :confuse: ? 1 mpg above EPA. Half those miles were with the incorrect fuel.

Now the range I have able to get has been interesting 44 mpg to 62 mpg.

lemmer

UK ratings have to be multiplied by somewhere in the range of 55-60% to get US ratings. So the 40 MPG would be 22-24 MPG here.

gagrice

Show me your proof. Here is mine.

http://www.sciencemadesimple.net/fuel_economy.php

lemmer

From my discussion with you on Jan 26 -

To see just how little relation European fuel economy ratings have to the figures on U.S. window stickers, let's look at the Volkswagen Golf TDI, a diesel compact sold in Europe and America.

VW's British Web site lists its fuel economy at 46.3 m.p.g. in the city, 68.9 on the highway and 58.9 in combined driving. The same car, with the same engine and transmission, rated 30 m.p.g. city/42 highway and 34 combined in U.S. EPA tests.

Part of it is their gallon is 20% bigger. The rest is completely different testing methods.

lemmer

The V10 TDI did 0-60 in about 7 seconds and got MPG in the teens.

ateixeira

I read the figure 8 results differently, is it a standing start or a running start? 0.6 seconds per lap is a huge lead.

Give the MDX taller gearing to allow the TDI to keep up, and the MDX would get better mileage.

Plus I'm paying more for diesel to begin with.

Base price $42,930 compared to $46,875, also.

Get a diesel because you want diesel characteristics, not because one anonymous guy claims he got 32mpg.

ateixeira

Face it we get sold the dregs

Maybe ours are also emissions choked? That could explain some of the difference.

busiris

Hardly.

You have determined the desired outcome and now want to justify your results.

Here's the correct answer....

If you don't have enough samples to make an accurate prediction, then you don't make the prediction.

That's exactly what professional statistical gathering organizations, including CR, do.

Basing my mpg estimate on how the FE will be for every driver in a car by driving 100 miles is meaningless, just as my basing the FE of a fleet of "cloned" cars upon the FE of a single vehicle with a single driver is meaningless...

Don't take my word for it.... Ask any high-school math teacher that teaches statistics.

Voting polls don't predict results for a presidential election after interviewing 10 voters at a single location...">

ateixeira

Yes but that sample is 2,450% bigger, so he'd laugh a little less.

gagrice

First the conversion is accurate. You are correct that they use different testing methods. We know the EPA is screwed up since making them fit hybrids. It is not exactly the same engine as we get here. They add more crappola to get by the [non-permissible content removed] at CARB. I would imagine that also costs a few miles per gallon.

Don't forget the 2009 Jetta Sportswagen TDI holds the mileage record for cross country travel. And the Touareg TDI holds the record for fastest time from the tip of South America to the most Northern spot in the USA. If the MDX was worth a hoot Honda could enter in the Dakar and show VW what for. hahahaha

Right now it looks like Mercedes will offer the first decent sized SUV with a 4 cylinder diesel that will get well over 30 MPG on the highway.

lemmer

If these guys were right and you really could get a huge increase in MPG with a diesel, would you buy one?

I wouldn't. I can't stand that they run out of steam so early. I like an engine that revs a little. Plus, VW and Audi have to increase their reliability a lot before I'll consider anything they make.

lemmer

This isn't 1978 anymore. Europe has stringent emissions requirements.

gagrice

I wouldn't. I can't stand that they run out of steam so early. I like an engine that revs a little.

Ah, that is the key here. I hate engines that have to get over 3000 RPM to produce any power. I loved driving the X5 with diesel. It just grunted and jumped from under 1000 RPM. I like cruising at low RPM and not have to listen to a screaming engine to maintain 75 MPH up hill. Different strokes for different folks. Give me the 700 mile range between fillups as well.

lemmer

Well, my sedan has 300 hp and 300 ft/lbs and cruises at low rpm. But I can't seem to top 22 mpg on the highway.

For me, a normally aspirated V6 gas engine is probably the best compromise of everything.

busiris

Well, I do think diesels will, on average, offer more mpg.

Then again, diesel fuel costs more, the vehicle is more expensive, and historically diesels have required more maintenance.... Probably because they lasted for so many more miles. Diesels are most efficient when they reach their normal operating temp, which doesn't happen in brief 5-10 mile trips.

Diesels make a lot of sense for one who travels 100K plus highway miles/ year. Running at a constant, lower rpm is the "sweet spot" for a diesel. And again, historically speaking, one can get a lot more miles out of a diesel engine as compared to a gas fired engine.

I've considered diesels in tha past, but my driving profile isn't suitable to the historic strengths of a diesel.

busiris

I understand. I drove a friends 2010 335d BMW, and the engine would "plant" you in the seat on acceleration!

ruking1

Not at all. EPA ratings despite being "imperfect" are in fact duplicatable. It is pretty easy to know for example how YOU drive and project what you could do in any car which you care to eventually get. Will everyone get that? Hardly. Yet the ranges given both in the bold print and fine print are pretty much the ranges of variance.

ruking1

..."I've considered diesels in tha past, but my driving profile isn't suitable to the historic strengths of a diesel."...

That is precisely the opposite reason why I prefer and use diesels because my driving profiles are. Not that gassers can't do it. Our driving is in the historical strengths of the diesels we have.

To be fair short trips are not good for gassers either.
"

stever

And again, historically speaking, one can get a lot more miles out of a diesel engine as compared to a gas fired engine.

I don't think holds true for the passenger fleet. Don't recall seeing any links to that effect at least.

My stat on that is Irv Gordon, and his 1966 Volvo 1800S that's pushing 2.6 million miles. 1966 is getting sort of historic.

Americans making cars last longer (telegram.com)

den0520218

If you could magically snap your fingers and turn every vehicle in the United States over to diesel, we could kiss OPEC good bye. Not that we would have cheap energy, but we would not have to import our energy. That is the efficiency of a diesel. Now with the electronic injection and start systems we have now, you would hardly know you have a diesel under the hood. The new ones have no smoke, start easily, and are quiet because of mulit-injection cycles the electronics are capable of. Instead of having one massive explosion at the top of the piston, new diesels inject a little fuel to start the burn, another one as the piston starts downward, and maybe another before the end of the stroke. That way you don't hear the knock as much and the injection is spread over time.
Master Vehicle mechanic and Heavy truck mechanic. I have 2 diesel rabbits that both get 55 mpg and NO I WILL NOT sell them.

ruking1

Well I think it would depend on what you mean by choking emissions. Here is an example which might illustrate that comparisons might be a little to a lot skewed.

03 Jetta TDI is standard in Europe with a 6 speed manual (one more gear and gears matched accordingly) 1.9 T diesel engine and .205 fuel injectors (larger)

In addition to the dumbing down to American standards, (yes it costs more money to give you a lousier product), the American version is standard with a 5 speed transmission and .184 fuel injectors (smaller, this and more mandated by the EPA) )

So as one can see it is hard to compare if you can not see it or drive it side by side. So not only does the European version get BETTER mpg 52 vs 50, it has a more powerful motor (10 hp more and 27# ft of torque more) and additional gear. So which one do you think I would rather have? Now I have not lived at all with the European version as it is not allowed in this country. Or not that I am dissatisfied with 50 mpg and the American Jetta TDI version.

ruking1

Perhaps a better population gauge would be your (edmunds.com) posting of the average age of the fleet going UP to 10.8 years old from 9.5 years old.

I can tell you that for "like miles" my 04 Civic took more maintenance and cost more than the TDI, given the same purposes (commute) ( $975.00 vs $600.00)

ruking1

Indeed !! My goal is a minimum of 500,000 miles !! I just love running them in their correct bandwidth. I run it on the open road at a little less than 60% rpms ( 56%, 5,100 rpm is considered REDLINE) Much over that and the 50 mpg goes down a tad and the Highway Patrol becomes interested.

gagrice

Welcome to the Forum, Young bright minds are always welcome. :shades:

Mr_Shiftright

the only longterm test results that we have on a diesel which are fairly current are for the 2011 Jetta TDI, and overall fuel mileage is 35.3 mpg.

Mr_Shiftright

Also there comes a point when increasing the number of samples really isn't necessary. How many times do you have to flip a coin before you conclude that it's 50-50 every time you flip? I don't think 10,000 flips gives you any different answer than 1000 flips.

so you know, you read enough longterm tests on TDIs and you "get the picture".

ruking1

Indeed to a certain extent that is true.

My response for the 2011 Jetta TDI's 35.3 mpg and for a 2009 Jetta TDI is that if I got 35.3 mpg, I would think something direly wrong with the car. The significance of the 2009 vs 2010, 2011, 2012 is the gearing on those is geared more for mpg than the 2009 (optimized if one will). But if OTHERS got that, it is WELL within ranges expressed.