Jetta TDI vs Hybrid on 1 Tank from Seattle to San Francisco

bulldog
the ac is a good one
the prius whit its electric AC will work a lot better then the jetta with its belt driven ac
if the ac was used the jetta will have a lot more trouble.

 

first you keep on lying
telling that the things those people where telling are right.
the prius battery last longer then 5 years cars already around with more then 10 years on them AND the total HP is a lot more then the 80 your tell those people
and the Torc of the prius is with 400nm a lot more then the jetta.....
so start telling facts and don't keep lying because then you really are giving yourself away being a troll..

second
when you drive the jetta sporty like and nog on the video like a grandma then you jetta TDI will not be so good......
and next time turn the ac on... lets see what good mpg you get then compared to the electric full rpm variable and compleet shutdown ( when cold in car ) ac from the prius.

 

Exciting is kind of a personal term. For some people, it's great cornering. The Prius is a gem at cornering compared to my Chevy Blazer, but it would probably lose to the TDI (but regrettably, I don't get to the mountains very often for it to matter). For some people, it's great acceleration. The Prius would be neck-and-neck with my Blazer, but apparently lose to the new TDI diesel (it would be a 3-way tie with the old TDI diesel). For some people, it's making a lot of noise so my neighbors know I can go fast. Oops, the Prius loses to both. For some people, it's getting 53.1 mpg over 1700 miles of driving so far. Thats a bit better than the 14 I coax out of the Blazer, and probably at least as good as the TDI driven by someone looking for excitement. For some people, knowing that your vehicle has a much better than average reliability rating is exciting. Not something to be said for my Blazer or the Jetta TDI. And of course, just surviving the drive is exciting for some of us. Both Prius and TDI would probably win out over the rollover champ!

That being said, let's see what the Jetta TDI can do- it's not a bad thing to have people getting better gas (oops, fuel!) mileage.

 

Until I bought my '08 Prius last week, I've had a 1997 Passat VR6, manual transmission for nearly 8 years. If the new Jetta TDI was available for purchase in the state of California, I would have seriously considered it. Despite high repair costs, I loved my Passat. It was fun to drive, had leather interior, great stereo, heated mirrors, heated seats, on board computer for gas mileage, power everything, moon roof (oh how I miss the moon roof already!), the seats folded flat with a wider cargo space than the hatch Prius.

I purchased a Prius for the following reasons:
1. Due to a 90 mile round trip commute, high gas mileage is a must. (CA, no new TDI, sigh...)
2. Lower repair costs (VW parts are extremely expensive- on par with BMW).
3. Lower new car purchase price.

Purchasing a Prius for many on the list is an eco choice - for me, it was a purely economic one. Don't get me wrong, I love my new Prius. But I will miss the control of the manual transmission and fast 6 cylinder engine of my Passat. I guess when I miss it too much, I'll just have to borrow my boyfriend's gas guzzling 6 speed BMW 540 (fire engine red, of course!).

 

I hear that a lot but question how useful it is to say the Prius has 295 lb-ft of torque because that's what its electric motor makes. At first thought, 295 lb-ft should smoke the Prius's tires at will but that doesn't seem to happen. With my understanding of Toyota's HSD, it seems that the Jetta will make more torque at the wheels than the Prius, despite having less engine torque. Let me explain. My Prius understanding is quite shallow so correct me if I am wrong.

The Prius MG2 is what makes 295 lb-ft of torque. It is connected directly to the output shaft of the PSD so no gear reduction takes place in the PSD. The Prius has an axle ratio of 3.91:1, so for each tire rotation, MG2 rotates 3.91 times. This means that MG2 can produce 295*3.91 = 1153 lb-ft of torque at the wheels.

Let us assume the Jetta TDI can make a relatively feeble 100 lb-ft of torque at idle. It has a 1st gear ratio of 3.77:1 and an axle ratio of 3.45:1. So that 100 lb-ft of idle torque becomes 100*3.77*3.45 = 1301 lb-ft at the wheels, already more than what MG2 will do. If we are after peak torque at the wheels, the Jetta will make 3070 lb-ft. I have no idea how to calculate peak torque for the Prius but think it is safe to assume it will be less than the Jetta.

So while that 295 lb-ft looks good on paper, it is not so big in the real world.

 

Being able to smoke tires could be considered a design shortcoming. Intentionally burning off a layer of rubber simply doesn't make any sense... hence features like TC and VCS. The by-wire design of the pedal contributes heavily too. When you drop it to the floor, the computer figures out how to prevent wheels from slipping.

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That's correct but you left out the torque of the gas engine. You need to add one third (PSD ratio) of the ICE torque before the reduction gear.

 

While the Jetta TDI is approved for all 50 states, you still cannot purchase in the state of California until it has 7500 miles on it. You can, however purchase a new diesel Toureg, go figure...

 

My VW experiences have taught me one thing!


Made in Mexico = Lemon Law

 

But you could do that with the previous TDI that wasn't approved for all 50 states. I believe the new TDI is legal for in all 50 states as a new vehicle.

 

My family owned a 1961 VW beetle. The reason that we bought it was that it was the cheapest new vehicle that we could buy at the time. There was certainly no consideration about it being a "fun" or "performance" vehicle. The job was to get 1 to 4 people from point A to point B in the most economical fashion.

As I recall, the only optional equipment was the fuel gauge and a fabric sunroof. It did not have a radio. The power was 40 HP, up 10% from the previous year's 36.

The most common problem with the vehicle was the rear bumper getting crushed so far that you couldn't open the engine compartment (engine was in the rear). The local VW dealer had a rather economical way of fixing the problem. They parked the car with the bumper over a crack in the driveway into the shop. Then they put an 8-foot crowbar into the crack and pulled the bumper out of the way.

The next most common problem was a dent in the rear fender. Practically nobody ever fixed that.

A minor service consisted of changing the oil, adding windshield fluid, and making sure that the spare tire had enough air. The windshield washer was powered by air from the spare tire.

The modern technology consisted of the 12 volt system. Earlier models used a 6 volt system. The battery lasted at least 7 years. If you ran the battery down, you could push start it yourself. It was much safer to have someone in the driver's seat and have someone else push the car up to 1-2 mph. Oh, and the car had syncromesh in first gear!

The way to hot rod a VW beetle was to drop in a Porshe motor. And for fun, you could install a Rolls Royce style hood. If you trashed the body, the next incarnation was a dune buggy.

The car was both fun to drive and economical. The emissions met the standards of the day, but could never achieve current standards.

Now that was a VW. The Jetta TDI is just another econobox that costs 10X its ancestor.

 

I found wheel slip useful a few times last winter when caught in deep snow. Probably not the smartest way to get out, but it worked. I have heard some about the Prius TC being over aggressive and cutting too much power. I'm sure you have come across a post from jayman on the subject. Some wheel slip is good to have in my opinion and I would prefer a system that limits wheel slip instead of preventing it completely. Has Toyota changed the Prius TC programming on the newer cars?

I was hoping to leave out the gas engine because it makes things more complicated Using http://eahart.com/prius/psd/ makes it look like MG1 will blow up if both the engine and MG2 are operating at their rpm for peak torque (4200 and <1200 rpm respectively). The gas engine can get up to about 3600rpm with MG2 running at 1200 before MG1 hits its limit. This happens at about 20mph. To make things a little easier, I'll assume that the gas engine can make peak torque at 3600rpm. So at peak performance, the Prius will send (295+82/3)*3.91 = 1260 lb-ft to the wheels, more or less on par with my low end estimate for the Jetta. Unless I am missing something else.

 

No, that's it. If you plot the gear ratios of a non-hybrid geared transmission car and compare it to the HSD speed / performance curve, you will get pretty much the same.

The difference is that, Prius does not need to shift gears and delivers consistent power to the wheel -- because gas engine, electric motors and transmission effect are tightly integrated together. The MG2 provides an instant 295 lbs-ft torque (pretty much covers 1st and probably into 2nd gear of a regular car) with a perfectly flat torque curve without shift lags.

I am sure you are aware of the Toyota published data. For 50km/h -> 80km/h acceleration, Camry and Prius take 5 seconds while Gen1 Prius takes 6 seconds -- despite a large peak power difference.



I tell people that gas and electric in HSD are like men and women. Both need to work together create the "feel good" result. :hug::rofl:

 

I've got 2.5 weeks to go for my vacation and am already bored to tears

Your statement is absolutely false

The modern refining process for diesel is actually far more carbon heavy than for regular gasoline. I covered all of this on my thread in Environmental discussion about oil refineries, including process diagrams

A lot of the aromatics that used to be flared off are sent through various isomerization and catalytic reforming steps to greatly enhance gasoline-range production.

The opposite problem is for modern diesel. First of all, a "light sweet" crude has far lower distillate - diesel - potential than a heavy sour crude. Another problem is that refineries have to produce ULSD to be compatible with DOC's and DPF's.

The only way to get current-source crude under 15 ppm sulfur is to extensively hydrotreat the residuum from every process step. That takes energy, and the use of consumable rare earth metals - catalysts - is really expensive

Strange how the diesel fanboys very conveniently overlook that picky little detail

 

You must have missed the post I made about trying out a new 2008 Prius, when there was still a bit of snow and ice around. The Trac behavior on the 2008 Prius is completely different from my 2004. It no longer kills all the power

 

I had not seen your posts on the subject but will go take a look shortly. The diesel fanboys probably overlook that because they don't spend much time on PriusChat with you. It certainly wasn't purposeful on my part, I generally considered that the GREET model would be reasonably accurate and I imagine some of the other fanboys assumed the same. Is GREET way off with its estimates? If so, do you know of a better source?

I did miss your post about trying the 2008. It is good to see that Toyota has improved their TC behavior.

Hopefully your vacation will get better.

 

GREET (Greenhouse gases, Regulated Emissions, Energy use in Transportation) is a complex, math-intensive "well to wheel" model. It is HIGHLY dependant on source crude, emissions systems, and other variables

For example, Light Sweet crude has lower distillate yield, but lower sulfur so much less hydrotreating is required. Heavy sour crude has much higher initial residuum and distillate yield, but needs extensive hydrotreating to remove the sulfur

The GREET models developed by Argonne don't present a clear advantage to diesel

http://www.veva.bc.ca/wtw/273.pdf

Consider that when GREET first came out, ULSD was not on the immediate horizon. Unless I missed it, I have seen no mention of particulate, NOx, or dioxin emissions that result from diesel engines.

The Union of Concerned Scientists did cover some of these issues

More Californians Killed By Diesel Pollution Than Homicide

The Diesel Dilemma: Diesel's Role in the Race for Clean Cars

For example, p 10 of the report

http://www.ucsusa.org/assets/documents/clean_vehicles/dieseldilemma_fullreport.pdf

briefly touches on the extra input energy required at the refinery to produce ULSD.

On p 16 the UCS contrasts the difference between the newer EPA-certified diesels and "clean" EU market diesels meeting EuroIV. For whatever reason, the Europeans put more emphasis on CO2 instead of smog forming, dangerous emissions. The report is mostly factual

 

I read your discussion on oil refining and while I didn't see any numbers, it was still very informative.

I apologize but I'm probably going to make your vacation even more boring shortly. Regarding the UCS report, on p.10 they have two charts. One is oil usage per gallon and the other is global warming pollution per gallon. You probably know better than I that more gasoline than diesel usually comes out of a barrel of oil so that's why diesel's oil usage is higher. I noticed that they did say "Since reformulated gasoline is a more refined product than low-sulfur diesel, its upstream emissions are slightly higher". That is what I was trying to say earlier.

Here are the two GREET-based studies that I have referred to in the past:

http://www.fuelcellpartnership.org/pdfs/ResourceDocs/Welltowheels/CEC Appendices.pdf
http://www.transportation.anl.gov/pdfs/TA/339.pdf

Both of them assume ULSD -- the second one labels it as LSD but if you search you will find that it's 15ppm sulfur which is ULSD. Appendix A in the first one and Appendix C in the second one break down well to tank and tank to wheels emissions and give the numbers. The second report also talks about PM10, NOx, SOx, CO, and VOC's, some of which may interest you.

 

Not sure how accurate some of these reports are, but a point to note on the second report (Appendix C) that the pollutants are shown per BTU of fuel. Thus translating it to volume/gallon will make the difference less between gas and diesel, by whatever factor seems to be appropriate.