Prius vs VW Diesel for Long commute

There is no such sweet spot at highway speed.
Above 42MPH, higher speed results worse mileage.

Ken@Japan

 

erm, I beg to differ. In the "warp stealth" state you can glide
for quite appreciable distances using no fuel. The ICE spins, but
it backs the valve timing way off for minimal pumping loss. It's
still better than burning gas, however minimally, to effectively
provide no power. I see about 10 amps from the HV battery during
this, which in fact is my main visual guide to holding the state,
and that small battery drain is going to keep spinning the ICE and
push the car along just slightly. In the region between 42 - 50
mph or so, where air resistance is still fairly low, using this
technique returns *significantly* better mileage. The cruise-control
may pop into this state by itself sometimes, which is why some folks
report good mileage from using it, but manual intervention can use
the ICE more efficiently than that.
.
Given that there's a fairly large accelerator-movement "plateau"
in which warp-stealth state is held, I would venture to guess that
this was entirely intended in the design. It's rather subtle and
not particularly easy to hold, but it really helps.
.
_H*

 

Hi Hobbit,

Using Wayne Brown's calculator,

67 mph requires 14 Kw
62 mph requires 12 Kw

You go 8% farther, but use 14/12 or 16% more energy. So unless the ICE is 8% more efficient at the higher speed, I do not see where your conclusions are coming from. My recollection of the power/efficiency curves is about a 2% change in these ranges.

I'm game to try out your method empiraclly though, if possible with standard instrumentation.

 

Do you have anything to back up this claim? I've been pretty strict about pegging my cruise control as close as possible to 55 mph so as to maximize fuel efficiency. Are you saying that if I bump up the cruise control to 65 mph, I'll actually do better? Being able to cruise at 65 mph is actually a bit more relaxing and safer than at 55 mph when I drive on Interstate 95.

 

Well, I think that the cars are so close it doesn't make a difference in MPG. The diesel engine will burn cleaner, because of amazing filter technological advances.

The real difference is honestly, which car you want. The VW offers amazing gas mileage, but if you ask it to, it will fly. My mom now owns a prius, but had taken the Jetta diesel for a test drive. While on the highway, she wanted to pass a car, and before she knew it, she was at 90 MPH... all that, just to take the next exit.

The Jetta diesel also comes with frontal, curtain, and side airbags STANDARD. You will be a million times safer in the Jetta TDI than in the prius.

Plus, the interior of the jetta is a lot more luxurious. It comes with either fake leather (really nice, not bad stuff), or leather interiors.
The Jetta also has rear climate vents, and seperate climate control for each side of the car.
It doesn't have the fun touch screen with all the nice features, but there is a red lcd crystal display that tells you outside temperature, instant MPG, average MPG, and other stuff.

Another thing you must consider with VW, is that they put a lot A LOT of research into engines. The engines are fine tuned for maximum efficiency and performace.

The Prius on the other hand has the hybrid factor, the silent starting, and stealth mode, and the power button, smart key system, rear camera etc. I don't have to go into details with the prius for obvious reasons.

So, it basically comes down to which car you want, based on other factors other than MPG.

Good luck,
-Sam

 

No way the diesel is cleaner than the Prius gas engine. They're so dirty you can't even buy a diesel in the most restrictive emission states, and the total number VW can sell is annually limited nationwide. To achieve lower emissions, very low sulfur fuel is needed, the last diesel reduction still leaves lots of sulfur compared to gasoline.

 

I knew someone would argue with what I said, but because of new filter technology, the diesels have almost zero emissions. You cannot compare a jetta diesel to a truck or something.

Like I said, vw spends a lot of resources on engines, and mechanical technic, and less on interior stuff, and filter technology was one of the really big factors. When I am around a running diesel engine, I can barely smell anything, as opposed to a running prius, which stinks quite a bit.

 

I posted this a month or so ago it's our local twit doing a real world hybrid and diesel road test it's worth a watch.
http://www.drivingtelevision.com/segmentvi...ent=2&segtitle=

 

Excuse me... you're extremely mistaken. Diesels still emit more NOx and significantly more CO2 than pretty much any hybrid.

I don't believe you understand the first lick about emissions. Do you know what your VW's CO2 emissions are? What about NOx?

Filtering on a diesel helps keep the amount of particulate matter from the diesel down, compared to a diesel without the filter, but you can't compare that to a gas burner. Your modern diesel vehicle puts out less soot than a diesel 20 years ago, but the fact remains that diesel technology is still much dirtier than modern conventional gasoline engines.

The Prius exceeds SULEV standards and meets AT-PZEV. THat means that the Prius produces only about 10% of the hydrocarbons, NOx and carbon monoxide than the average vehicle out there. What's your Diesel's rating on the CARB scale?

I'll save you some time in looking it up. It fails to met LEV standards because of the NOx. For that reason, YOU CAN'T BUY A JETTA TDI IN CALIFORNIA, OR THE NORTHEASTERN STATES. that's a fact.

You're very much mistaken.

 

let's look at the numbers, shall we?

Jetta: (look for the diesels, they're easy to pick out by the pollution scales)
http://www.epa.gov/emissweb/E-VOLKSWAGEN-Jetta-05.htm

Prius:
http://www.epa.gov/emissweb/E-TOYOTA-Prius-05.htm

 

So does the Prius. Prius has side curtain for both passenger and driver, side for both, front, and passenger SRS...

The Prius comes with Traction control and ABS standard, and has vehicle stability control available on all but the most basic package. Does the Jetta?

 

Great find Galaxee.

I like to look at the map for those diesels and point out how California, New York, Massachusetts, Maine, and Vermont are strangely absent from the availability of the TDIs... because, once again, they are far too dirty for the higher standards of those states.

 

working in science, i've learned sometimes the most effective argument is just to shut my mouth, present the data and let it speak for itself.

 

The Jetta also has Traction and Stability control available, if not standard, depending on the package. And adjustable seats and a telescoping steering wheel.

And according to the NHTSA, the Jetta was one of the best cars tested, getting 5 stars all around. I think the Prius got a combination of 5 and 4 stars. So it is not as safe.

 

Duplicate post. Whoops.

 

Jettas are GREAT cars. I've had one since 1999. I don't have the TDI, but I get about 30mpg with my 2.0. It has great pickup and even after all these years, the leather and interior look great! It really does a great job of giving you the feeling you're in a high end luxury car. Did I mention it's VERY fun to drive and I only paid $19.5k for it? I think Jettas are hard to beat as far as the features and german quality you get for the price. I don't expect to have such good "german" quality when I buy my japanese car.

Now for the bad stuff, if you've seen the excel doc posted on the first message, those repairs are typical for a VW - not just a TDI. My car has about the same amount of repairs... just random crap breaks that adds up over time. For this reason, I will NOT be getting another VW and I'm going back to what I know that normally has low maintenance cost: Japanese cars. So more than likely when I buy a car it'll either be a Honda, Toyota, Nissan and the like. I wish the Hybrid Altima would be out all over the US when I'm in the market.

If Jettas had a lower repair rate, I would definately get the newly designed ones. They look very elite and it's tempting... Everytime I get my car repaired, I go and sit in one. Unfortunately, I've sat in them several times... which in a sad way reminds me not to buy.

 

sorry, but my definition of "quality" does NOT include frequent trips to the dealer...

which is why we drive toyotas.

 

Could you possibly be more wrong?

I doubt it.

These 'amazing' filter technologies MAY allow diesels to BARELY meet the MINIMUM emissions requirements to even be sold in CARB states AFTER we get Low Sulfur Diesel everywhere.

Of course, there's no guarantee of that because these amazing filters don't exist yet. We'll see in a year or so what they actually are.

To compare the cleanest diesel in the world to any SULEV II car, much less a Prius is worth a hearty belly laugh.