Why no diesel Prius?
 

I first starting ecomodding by running veggie oil in my diesel

During my research I ran across many different diesel swaps
one of them being a diesel engine swap for a Toyota Previa.

That swap allowed it to run on waste vegetable oil.

So why is there no diesel Toyota Prius yet?
(or at least a diesel engine swap for one)


My first thought is that the system is designed EXCLUSIVELY
for the prius making additions incredibly difficult.


But imagine a car that ran on electricity being recharged by waste vegetable oil.
Hard to get greener than that.


Especially since the golf has been deemed too expensive.

Diesel technology is more expensive, and Toyota had to cut corners somewhere.

alohaspirit -

Speculating offhand, Diesel has a bad rep in Japan (maybe worse than in the USA?!?!), what Piwoslaw said, and it would be harder to make it emissions compliant in the USA. Wouldn't a Diesel also weigh more?

Hrmmmmmm, what is the smallest displacement Diesel that Toyota makes?!?!?

CarloSW2

It may be this one: Toyota ND engine - Wikipedia, the free encyclopedia
There is an aygo using the same engine here: 90mpg Aygo - Toyota Owners Club - Toyota Forum
I thought it may be smaller than 1.4 but it's not.

Anyway, back on topic. I believe another reason a diesel hybrid was not made is due to the diesel not coping too well with the constant on/off. Turbo issues i suppose.

ollie

The reason nobody's done it at home is twofold. One, the stock engine is pretty darned efficient, and there's little room for improvemnt in CO2/mi or even gal/mi with a diesel. Two, there aren't a lot of cheap Prii with dead engines, because the stock engine tends to outlast the car.

Japan also hates diesels, :)

Toyota's goal was to make one of the cleanest burning cars that also got good gas mileage, if they were going for just mileage they would have done better.

I can't support this claim at all.

Diesels are typically ~30% more efficient (fuel used per mile) than gasoline engines, right?

So how is there "not much to gain" from using a diesel with the same hybrid system?

I don't remember seeing a suggestion to take out the hybrid setup, just to use a diesel engine instead of gasoline... that would make the Prius ~30% more efficient on diesel.

EPA rating for the Prius Gasoline Hybrid is: 50C/49H

30% higher than 50mippigs is 65 mippigs... I'd rather have the latter, and that's the "we're not really going to try" EPA estimate.

Christ -

I agree in the long run. A good hybrid design would allow for transplanting the "emission portion" of the powerplant. I think that from a strategic market standpoint, a non-Diesel was the way to go. Like SVOboy said, diesels are frowned upon in Japan. The Prius was tootling around in Japan's protected market for four years before it got here. It was "growing up" in Japan and getting the bugs out, from my POV.

Toyota Prius - Wikipedia, the free encyclopedia
I second vtec-e's question. What about the constant on-off? Don't diesels like to keep idling at stops to be more efficient?

CarloSW2

Well then let it idle at a stop light, charging the bateries at a slower, but constant rate.

Diesels have such a low redline b/c of weight and other factors, but weight plays a major role in keeping engines running as well. A diesel engine tuned properly could idle as low as 50-75 RPM (So can 225 slant six gassers, but you'll smear the bearings.) With a properly designed oil pump that could function at a speed that slow, you'd almost never notice the fuel consumption from idling a few minutes anyway. Not to mention that under 0 load, idling, the diesel runs so insanely far from stoich that it's uncounted anyway. They literally use *just* enough fuel to keep running, and they use very little to maintain 1000 RPM or so... imagine 50RPM.

NVH is the real problem here.. you'd have to seriously balance a diesel to keep it from wiggling your eyeballs out of your head at that low engine speed.

Theory behind keeping a diesel running: They like to be hot. Hot. HOT. Hotter - better for fuel combustion, less energy necessary to heat up the air enough to combust the fuel = more efficient. That's all. It's not that you can't stop and start them, it's just that they're less efficient the cooler the motor is. Same with gassers, but more pronounced and obvious. That said, once they heat up, they don't lose that heat very quickly. Remember, most diesels are basically cast iron bricks. Sure, you'll lose a bit of efficiency each time the engine starts, for a few seconds, but you're only using it to accelerate anyway. Under load, it will heat back up very quickly. I'm sure they could insulate the engine as well, making it keep heat longer.

I still like the 50-75 RPM idling idea, though.

petro diesel is unthinkable at this point

Ideally hybrid diesels would open the door for biodiesel or svo

creating another truly green vehicle

Bad... Bad.

SVO and WVO are both not very good for people... well, the exhaust from them isn't.

You're burning glycerin and triglycerides, which only burn completely at very high temperatures... higher than your engine gets them. You end up expelling very dangerous gasses, and for the time you spend with WVO filtering and blahblahblah playing with it, it's the same time you'd spend making BioDiesel out of it, at only slightly more expense, but ending up with a much higher quality fuel.

AAMOF, it's technically illegal to use WVO or SVO in cars on the road... the fine is the same as using HHO (Home Heating Oil, not that other crap) for fuel, because it's not been mandated for on-road use by the EPA or NHTSA.

wvo is far from perfect

but alot of that oil contain no sulphur,
so SO2 gas is not present when running on those oils

CO2 emissions are also reduced
Some by as much as 80-90% when compared to petrol diesel

not to mention the metric tons of waste oil not going into a landfill somewhere



The biodiesel process is very caustic
Id rather leave that process to people who can
dedicate the proper space to its production
(ie: not my townhouse)

as far as it being illegal i think we're ok
EOC isnt exactly legal either

The Prius uses an Atkinson cycle engine:

• 8-to-1 compression stroke - this is accomplished by leaving the intake valve open during nearly half of the compression stroke. Part of the charge is pushed back into the intake manifold but be drawn in by another cylinder. This also reduces the amount of energy needed to turn over the engine and reduces internal, power robbing, friction. In contrast, the diesel requires a very strong motor to overcome the 20-to-1 compression stroke.
• 13-to-1 expansion stroke - the exhaust stroke provides a ratio that allows a very high ratio of energy extraction. A typical diesel is 20-to-1 so the Prius brake specific fuel consumption approaches diesel with the advantage of a significant reduction in NO{x} production.
• avoiding low-power, inefficient operation - the electric part of the Prius allows the engine to run at a higher power but very efficient range than needed at slow speeds and it stores the extra energy in the battery. Then the engine shuts down and the stored electrical energy powers the car without burning any more fuel. This advanced transmission is what is missing from diesel vehicles which at lower power settings has to always deal with engine friction losses, a lower BSFC than the Atkinson engine.
• saving brake energy - another part of the Prius is saving braking energy as battery charge for use later. This is another part missing from diesel vehicles.

What it comes down to is the diesel doesn't offer enough to compensate for its short-comings: (1) higher NO{x} emissions, (2) inefficient at low power settings, (3) absence of regenerative braking, and (4) difficulty handling start-stop engine operation. They also tend to be heavy.

It is likely that as combustion temperatures are mastered, some future engine may support super-lean yet NO{x} safe systems. Perhaps some clever combination of cooled exhaust temperature and direct fuel injection but right now, these are discussed in university labs, not really in production vehicles ... except for the 2010 Prius.

At high power settings, the 1.8L Prius engine cools part of the exhaust and feeds it into the intake manifold. This reduces the peak combustion temperature so the Prius BSFC remains high even climbing a hill at high speed. The mixture remains lean but the engine doesn't burn out the catalytic converter or overload it with NO{x} products.

The Prius also uses fuel injection but not to direct combustion. Instead, the fuel is carefully metered and there is time to achieve an optimum fuel-air mix for combustion. In contrast, the diesel is always 'lean burn', it has to be, and that leads to NO{x} and other problems. It is the Atkinson cycle, the reduced fuel charge at low power settings that gives it the "on the road" advantage.

Bob Wilson

Apples to Apples, the gasoline engine currently in use by the prius also doesn't have regenerative braking. The electric motor stored in the housing on the back of the gasser's block is what creates that function.

Diesels have higher NOx production, yes. But there are systems in place that can work with that.

Diesels aren't inefficient at low power, they're inefficient at low LOAD... same thing with gas engines. Diesels can be run as low power as you want them, provided the engine's dynamic displacement compares to the power being created. (This is where EGR comes into play.)

At high power settings, the 1.8 Liter Prius engine uses excess EGR flow to fill the combustion chambers, which decreases dynamic displacement, keeping BSFC higher by lowering cylinder temps.

Diesels don't have difficulty handling start/stop operation as much as people like to think. Talk to a farmer some day, who runs diesel tractors.

As far as being heavy, compare the power to weight ratio (and potential power to weight) of a diesel to a gasser... they're about the same. The diesel has the potential to produce the same horsepower at the same weight (meaning smaller displacement) than a gasser.

Its easy to find a diesel electric hybrid.
Only catch is they are all on tracks.

Oh, and
Before I put on the grill block and electric fan, my temp gauge never went above the 1/4 mark.

Now it stays around the 1/2 mark.
I shut the engine to avoid idling all the time, a 2 minute stop light is not long enough for it to budge. In other words, any loss of heat from being off is negligible.

I think there are no diesel hybrid cars yet because there are very few hybrids, and also very few diesels. Someone will come out with one eventually.

One word...

ok, i lied. heres a lot of them



70 miles per gallon, a 7-speed direct shift gearbox (DSG) with a twin-clutch, minor modifications to reduce aerodynamic drag, CO2 emissions of 89 g/km (lower than a Toyota Prius hybrid), and Tier 2 Bin 5 tailpipe emissions. And of course, the ability to run on biodiesel (waste cooking oil or even algae).

But it was too good to be true. VW contradicted its earlier statement in the March 27 issue of Auto, Motor und Sport and said that the Golf turbo-diesel hybrid would be too expensive, so they're not going to make it. (A diesel that is)


R.I.P. Golf Turbo-Diesel Hybrid. We hardly knew ya.

Revealed: Volkswagen’s 69.9-MPG Diesel Hybrid | Autopia | Wired.com

http://www.wired.com/images_blogs/au..._hybrid_01.jpg

Pet Peeve #87: Idle damn diesels all the time. :mad:

They can start and stop just as well as anything. There is no reason why they can't.

Stupid *holes with diesel vehicles tend to let them idle for hours on end. Why? Damn thing has a starter right??? :mad:

Only exception I can see for that is when it's -40F out. Even then, shut 'er off and restart in an hour or so for a while.

We call that "gasser's block" the transaxle but I'll adopt your curious term, "the back of the gasser's block."

Both a diesel and a gas engine require a minimum amount of fuel burn to run at idle. Call this the 'heartbeat' or minimum operating fuel burn rate. If the engine, diesel or gas, requires double that amount of fuel to provide the "low LOAD," the efficiency has increased over idle, a little bit. But the Prius plays a trick with its "the back of the gasser's block" (called a transaxle.)

The Prius produces much more energy than is needed by the load so the engine 'hearbeat' or minimum idle burn rate is a small fraction of the total fuel burn. The energy in excess of what the vehicle needs is converted into electrical energy stored in the battery. Then soon as there is enough energy in the battery, the Prius gas engine shuts down and the stored energy in the battery is used to move the car. Thus a larger portion of the Atkinson cycle energy is ultimately used for vehicle power compared to the diesel that is running in a power range that a significant portion of its energy just meets the 'idle power' need.

In contrast, the diesel-only car at "low LOAD" continues to pay a significant portion of its fuel burn just to keep the engine running. Without an integrated "the back of the gasser's block" (called a transaxle,) the diesel performs poorly at "low LOAD" (aka., city driving.)

So what do you call a diesel transmission or transaxle, some sort of "the back of the diesel's block?"

The problem is the minimum energy needed at idle remains a significant portion of the energy burned just to keep the engine turning over, the 'idle fuel burn.'

Now part of the internal friction comes from the piston rings having to seal the gas pressure. On the compression stroke, the diesel goes from 20-to-1 whereas the Atkinson engine Prius goes from 8-to-1. The Prius has a lower pressure load on the rings than the diesel. Then comes the power stroke and both are dealing with similar pressures and friction.

All I know is what I've read in SAE 2009-01-1061, "Development of New 1.8-Liter Engine for Hybrid Vehicles" Kawmoto, Naiki, Kawai, Shikida, and Tomatsuri, Toyota Motor Corporation:
http://hiwaay.net/~bzwilson/prius/pr...1061_pp4_1.jpg

http://hiwaay.net/~bzwilson/prius/pr...1061_pp5_1.jpg

I didn't see them using "dynamic displacement" to explain what is going on. Is that some sort of diesel term?

Usually it takes a little more torque and energy to turn a crank against a 20-to-1 compression stroke than an 8-to-1 compression stroke for identical displacement engines. Having cranked a Model A Ford before, I remember the effort needed.

<sigh>Yes of course, the 'potential' is always there.

Bob Wilson

I don't think we have the final word, yet. It is becoming difficult for non-hybrid companies like VW to ignore the Prius sales and the continued performance improvements. Sad to say, they still don't understand the engineering.

I'm afraid we are likely to see 'greenwash' hybrids ... large fuel engines with tiny electric motors. This was the secret to GM's success ... 'greenwash'.

Bob Wilson

.

Hi,

I would recommend getting a copy of SAE 2009-01-1061, "Development of New 1.8-Liter Engine for Hybrid Vehicles" Kawmoto, Naiki, Kawai, Shikida, and Tomatsuri, Toyota Motor Corporation, and SAE 2009-01-0726, "Development of New Hybrid Transmission for Compact-Class Vehicles" Mizuno, Ibaraki, Kondo, Odaka, Watanabe, Mizutani, Kaneshige, and Kitada, Toyota Motor Corporation. The first fully covers the new 1.8L engine and the later, the transmission. However, these are not 'systems views' of the 2010 Prius and many times, a general discussion can help clear up some misconceptions.

The Prius engine 'cheats' the pumping losses by using an Atkinson cycle that keeps the input valves open during half of the compression stroke. Such simple words belie what is going on. It is an intake valve trick that significantly reduces pumping losses seen in an Otto engine but requires doubling the number of phases involved to understand:

Phase angle - Otto cycle - Atkinson cycle
0-45 - power stroke - power stroke
45-90 - power stroke - power stroke
90-135 - exhaust stroke - exhaust stroke
135-180 - exhaust stroke - exhaust stroke
180-225 - intake stroke (pumping loss) - intake stroke (pumping loss)
225-270 - intake stroke (pumping loss) - intake stroke from adjacent cylinder (no pumping loss)
270-315 - compression stroke - push charge to adjacent cylinder (no pumping loss)
315-360 - compression stroke - compression stroke, half charge

The Atkinson cycle trick occurs at angles 225-315 when the intake valves of two cylinders, one beginning compression and a second beginning intake, where the charge passes from the first cylinder to the second cylinder. There is no 'pumping' loss during this ~45 degree phase. But the variable intake valve also replaces part of the traditional throttle plate function.

Now if you'll re-read page 5 from SAE 2009-01-1061, the 1.8L engine paper, you'll notice the intake valve has a variable range of 41 degrees. This change in intake valve opening replaces some of the throttle plate by controlling how much fuel-air leaks from one cylinder to the next. In a traditional Otto engine throttle, all of air intake has to push through that narrow gap. In contrast, the Atkinson cycle is just passing part of the charge from one cylinder to the next without the throttle plate, narrow gap. But these are details of implementation whose real impact shows up in vehicle performance.

The bottom line, "the proof," is in the mileage numbers from an engineering lab, like the EPA requires, as found at www.fueleconomy.gov:

City - Highway - vehicle engine
51 - 48 - 1.8L, 2010 Prius
29 - 40 - 2.0L, 2009 Jetta TDI

The outstanding Prius mileage is a product of the Atkinson cycle engine and efficient transmission/transaxle combined with a sophisticated set of control laws. One's understanding or lack of understanding of these Prius systems doesn't really matter when standing by the fuel pump and paying the bottom line.

I am reminded of the story of the aerodynamic analysis of the bumble bee that proved they could not fly. Yet there they are, buzzing around. It is possible that the problem was not the bumble bee but the limited, aerodynamic analysis. There comes a time when old concepts have to be replaced by improved understanding.

So let's assume that the starting motor power is the amount of energy needed to spin an engine at idle. This is a fair approximation of the minimum energy losses of each:

• 20-to-1 diesel - the high compression resistance requires a lot of torque, more power
• 8-to-1 Atkinson - the low compression resistance requires less torque, less power

Meanwhile, the overlapping, open valve of the intake and compression stroke further reduces the 'idle' fuel burn but the Prius has one more trick ... it turns off the engine. Unlike our diesel friends, the Prius turns the engine off and runs on the stored traction battery energy until more power is needed.

These are not easy concepts to master, especially after a life-time of dealing with traditional Otto and diesel cycle engines and traditional passive transmissions. I'm hoping our diesel friends might get a clue. If they do, good. If not, no matter, the EPA numbers are accurate.

Bob Wilson

You're also still not comparing apples to apples. I've read both of those papers before.

You're comparing a gas/electric hybrid to a "clean diesel" which is not a hybrid. The city efficiency of the Prius comes from the e-motor driving it when power from the gas engine isn't necessary.

If you want to compare apples to apples, you need to compare the Prius's gas engine ALONE to the Jetta's "Clean diesel", no hybrid action at all.

I'm also very familiar with the Atkinson Cycle engine and it's concepts. Saying that there are no pumping losses while the engine is pushing air back out of the cylinder and into the plenum so that another cylinder can draw it in is completely false. Yes, there are less pumping losses, but they're not gone.

Instead, what you now have is an engine that is pumping air back into the plenum, already mixed with fuel, so that another piston's intake valve can open, draw in under vacuum the pre-mixed air and fuel, with a little more air, and a little more fuel, so that cylinder can pump some of that mix back into the plenum, so another cylinder.... blah blah blah. The engine really isn't that hard to understand. Comp Cams built a package for race engines in the 70's and 80's that allowed people to run 19:1 compression on leaded gas, which followed that same principal. This is also where dynamic compression and dynamic displacement come into play.

19:1 static compression means literally nothing when designing an engine. You can build an engine to a MUCH higher tolerance than that, drawing in a full cylinder (100%VE), as long as you're not compressing a full cylinder. This is where the Atkinson Concept camshaft comes into play. If the camshaft allows part of the air charge back out of the cylinder, you can run an insanely high compression ratio, with better efficiency per unit of fuel used, than a traditional Otto Cycle engine.

So sure, your Toyota's Atkinson Concept engine (It's still not a true Atkinson Cycle engine) might have less pumping losses per unit used, but it's also making MUCH LESS power per pound (both pounds of engine weight, and pounds of air drawn) by having to process that air in a non-linear fashion, several times, without actually making any power from it.

Guess what? Diesel engines could use (probably not benefit from, but use) an Atkinson Concept camshaft design as well.

Diesel prius would be stupid expensive and diesel engines have trouble meeting emissions regs when the engine is starting which a hybrid does a lot of. Besides, gasoline engine is cleaner, qieter, lighter and much cheaper to build. I would rather they invest more money into the electric side instead of the ICE. By the way, the prius already uses an atkinson cycle engine. Look that up some time.

Diesel prius would be stupid expensive = Yes

diesel engines have trouble meeting emissions regs = No

Besides, gasoline engine is cleaner, = :confused:

qieter, lighter = A little

and much cheaper to build = Depending

I would rather they invest more money into the electric side instead of the ICE. = Do you drive an electric car?

Hi,

I'd hold off on calling anything "stupid" but rather point out that engineering often entails trade-offs to find if not an optimum, at least an acceptable solution. I was hoping to make sure we're all on the same sheet of paper with similar understanding and that seems to be the case. Then comes the detailed analysis.

In words, we've described all of the elements (hopefully for lurkers who may not have understood some the fine details.) The next phase would be to load this knowledge into a model and run the simulations. Will there be a compression-ignition, hybrid vehicle in the future, I don't know. There isn't one in production, yet, but that might change.

I note that the chairman of VW in the first week of July talked as if they are going to move towards vehicles with a significant, electrical motive capability. He correctly identifies this as a long-haul goal and my best guess is:

• 2-3 years - engineering design time
• 1st generation - needs about 3 years of road time for 'lessons' learned
• 2nd generation - fixes worst, still has some problem areas, 3-5 years
• 3d generation - what the 2010 is today

Right now, I can't get excited by the current VW diesels, their metrics don't work. But VW may have seen 'the writing on the wall' and it will take them a little time to get something designed and in the market place. I just hope they don't follow the GM model and make "greenwash" hybrids whose electrical parts are little more than glorified alternator/starter motors.

Bob Wilson

Its a really hard market for the masses,
almost like trying to tell people to skip Mcdonalds and drink more clean water

probably the story of our life


which is why the Gen1 Insight died
no one wanted a small 5 speed 2 seater

same reason why small electric cars dont take off
because people dont "feel" safe
http://www.jdlh.palo-alto.ca.us/pr/s...PIM0619med.gif


Honda copied the Prius due to mass appeal

Tesla followed suit

Conclusion:
Most people want Prius-size cars first, upgrades second, cost third, global impact last

http://img3.allvoices.com/thumbs/eve...esla-sedan.jpg

More torque but less duration, most diesels will start in one single compression cycle once warm, I do not know of any gasoline motors that can do that repeatably.

Your statements are mostly false, my 1982 diesel suburban once warm starts nearly instantly and emits no additional exhaust during warm startup than normal. It always amazed me that I could turn the key into start and back out as fast as I could move it and the motor always started fine. Truth be told there have been instant on/off diesel prototype cars floating around since the 80's most could start in ONE compression cycle unlike a gasser that always needs some degree of cranking duration. A simple spring was used if I remember to kick the motor off and on rapidly.

Diesel emissions are much more cleanable than gas emissions, lest we forget mining operations almost always use DIESEL equipment underground with a water wash on the exhaust because gasoline emissions are not easily made NON Lethal in enclosed spaces. On a diesel, All you end up with is a reduced amount of CO2 and water for air born emissions as compared to cleaned gas emissions which always include Carbon monoxide. Why people are unwilling to make a bit of fertilized water (which can be recovered and reused ONBOARD electrically mind you) on their diesels is beyond me, diesels DO NOT need to emit any airborne emissions besides CO2 even with high sulfur fuel with a simple water or saltwater wash. True fertilizer and water use is irritating but considerably less than smog I would guess?

Another word of note is that Diesel engines can be built for about the same price as gasoline engines, they just are never marketed that way (aka artificial inflation, lower demand). The real price difference in labor and materials is trivial. Diesels DO NOT need to be as complex as they are being made, to compete with a gasser, the emissions non-issue is what is making the problems. And the solution for diesel emissions has been known since the 40's, sadly only ocean going vessels and miners see the solution.

Cheers
Ryan

Ironic, isn't it? Noone wants a small 2-seater, even though on average there is something like 1.2-1.4 people in each car. Yes, most people drive alone, almost noone takes on more than 1 passenger. Yet they want a big 5-seater. In fact, most people want a big SUV, 4x4 etc., even though they never leave the pavement. A 70kW engine is more than enough for their driving, but they have to have a 150kW V6 under the hood. It's not about what they need, it's about what they might need.

Because bean counters always win, that's why.

New sig quote. Thanks!

Hi,

I finally got tired of not finding a web page describing how a modern Atkinson engine works so I made my own.

Bob Wilson

Wooo, nice page Bob. Thanks for the time you put into it.

The whole talk about the Prius being more efficient than a diesel got me thinking. Here is the comparison I came up with to put things in to perspective.

My dad drives a 2005 Dodge Ram 2500 Quad Cab longbed 4X4 with 5.9L diesel Cummins engine. The truck gets as much as 22 mpg hwy.

A 2005 Volkswagen Jetta Wagon TDI gets 43 mpg hwy. A 2010 Toyota Prius
gets 48 Hwy.

I compared the Hwy mileage of all three vehicles because in city driving the Prius heavily uses the hybrid system which makes it not an equal comparison to the other vehicles. Also I picked a 05 Volkswagen Jetta Wagon TDI because its the same year diesel as the Dodge and weighs almost exactly as much as the Prius. Also this is the fuel economy from all three vehicles that are automatic.

First off the Dodge's engine is a little over 3 times the size of of the TDI and the engine weighs approx. 1,150 lbs that's 376.5 lbs short of weighing half as much as a Prius. The Dodge's Curb weight is 7500 lbs. That's about about 2.5 times heavier then the Prius or jetta.

The 05 Volkswagen Jetta Wagon TDI curb weight is 3,053 lbs. and has a Drag coefficient of .32

The 2010 Toyota Prius Curb weight is 3,042 lbs and a Drag coefficient of .25

The Dodge is ugly when it comes to aerodynamics and to make things worse it has a shell that sticks up over the cab.

The Volkswagen gets pretty close to the same fuel economy as the Prius for being less aerodynamic and not a hybrid. The Dodge gets half the mpg of the VW and slightly less then half of the Prius not bad considering the difference in aerodynamics, vehicle weight and engine size. To sum things up I don't see why a diesel with a properly sized engine and aerodynamics like the Prius wouldn't get as good if not better fuel economy. Also wouldn't the Dodge get as good if not better mileage then a Prius if it did not weigh 2.5 times as much and have an engine over 3x has big?

On a side not the new Volkswagen TDIs have a bigger engine and more hp then the older TDIs but still get about the same fuel economy.

I think the biggest reason for hybrids to exist is the stop n start city cycle. Personally they don't make sense to me if the bulk of one's driving is highway.

Woa, no wonder the 02 TDI I have coasts like a brick without wheels.

youve obviously never driven in my geo tracker

Alohaspirit -

I want a tracker, so I can lower it and swap in a G10T. :)