Toyota mulls whether to change Prius look to widen appeal

The most aerodynamic shape of a vehicle going under 60 mph is a rain drop (something like a modern nuclear attack submarine or a boxfish as usbseawolf 2000 points out). Some people have added boattails to their cars on Ecomodders.com to reduce the fuel sucking effects of wind turbulance on their vehicles. IIRC adding a boattail to a car adds about 7 mpg in FE. This design shape also goes for airfoil designs as well until the speed increases to about 450 mph. In addition, each additional wheel over two wheels that touches the road adds more rolling resistance (however each additional wheel increases the vehicle's road surface contact area and increases its road traction and handling performance). Overall, the most significant factor energy efficiency factor (and the most cost effect route to FE) is to reduce a vehicle's mass/ curb weight - the lighter the mass of the vehicle the less energy is needed to keep it in motion, e.g. Edison2 VLC.

 

Like the Ferrari , the Prius' low front airdams and black plastic cover underneath doesnot have much road clearance so potholes, uneven curbs and driveways can be potential road hazards. The Ferrari can goes much faster than a Prius but the local traffic here is so bad and the speed limit are so low - Ferrari end up not going much faster than a Prius. To add insult to injury, the Prius not only gets better MPG, more seating and cargo space than a Ferrari - it is signficantly less costly a ride .

 

The look of the car is important for sales, and the camback prius design helped. Neither it nor the tear drop are most slippery for a car. This VW design, similar to the EV1 appears to be most slippery.

Volkswagen XL1 Test Drive - MPGs in the One Liter Car - Popular Mechanics

Note it has a lower hood and different rake to the windshield as toyota is talking about. The cd is .19, 24% less than the current prius, and it has a much lower frontal area also. The tail of the car reduces turbulance. There are trade offs between interior space and looks for the aerodynamics.

Let's face it 2 wheels carrying 5 people will never be close to as safe or stable as 3 3 wheels can provide great manuaverability and lower rolling resistance, but this thing is going to be a car with 4 wheels.

The hybrid power trane breaks this completely. Adding a battery and motors makes a heavier vehicle more efficient. Weight is also needed for decent suspension and a quiet ride as well as safety. You can't drop much below the 2500 lbs of the aqua/prius c, without using expensive material like carbon fiber. The prius c gets the same epa combined as the much heavier prius phv in cd mode. That prius phv also allows you to drive for miles on electrons. The rumor from motor trend was a drop of about 5% of weight. That will maybe up city mileage by 2mpg and do nothing for highway mileage.

 

Anyone remember the old AMC Pacer?
That was sort of Prius-like, way before Prius.
I like the liberal use of glass, as far as visibility.
It was considered a unique looking car.

 

The Volkswagen XL1 body and 0.186 drag coefficient is similar that of a 1999 Honda Insight. However, the vW's 0-50 mph in 32 seconds is too slow to be practical - basically the VW 8.5 HP engine was too weak - VW should have mated a 42 HP engine to it instead and focused on getting something less like 100 mpg. What is exceptional with regards to the VW XL 1 is its much lower 640 pound curb weight which is achieved by using of a carbon fiber body -this drop its curb weight of over 1000 pounds from a 1999 Honda Insight (iirc the lightest Insight was about 1800 pounds) which depended using aluminum to shed its pounds.

I agree that 3 wheels and 4 wheels are more practical. It's just that motorcycle configuratin has a higher FE potential.

Past vehicle designs suggest to me that 1700 pounds is the bottom limit to curb weight when it comes to the modern expectation levels in vehicle comfort, safety, and handling. I agree that a hybrid's increased fuel efficiency is partly due to recapturing and reusing energy normally lost during braking - however this energy recapturing and reuse process is only 30% to 50% efficient. When I suggest a reduction in curb weight -it is with the intent of either maintaining or increasing HP/curbweight ratio at the same time - this would improves stop and go urban/city MPGs, the mountainous/ hilly terrain fuel efficiency, and highway MPG levels (but not as much as the city MPGs would improve). To get a significant improvement in a vehicle's highway fuel efficiency - the frontal wind drag area has to be reduced and you have to add a boat tail to reduce drag from turbulence.

 

Your reading L1, the XL1 is a 2 cyl diesel phev. The ice is 47hp, but the battery and motors supply an additional 27hp for a 11.9 seconds to 100 kph, just a little slower than a prius. It should get mid to high hundreds of mpg depending on how fast you drive. The original insight had a cd of .25 like the prius, much higher than the ev1 or this xl1. Because of the small frontal area, the xl1 only has 59% of the drag of the original honda insight.

That is L1 also, which had seats behind each other. The XL1 with the big battery and side by side seats weighs 1795lbs around the same as the insight. That big battery will greatly boost city mileage even if you don't plug it in. I'm sure that L1 would have crushed any car on the highway ;-) I'm sure you could shave weight in that battery if you wanted a pulse glide car

2 wheels have an advantage at low speeds. At higher speeds 3 wheels allow for a more aerodynamic car, which gets more fuel economy. If you want side by side seating instead of front back at least 3 wheels is the minimum.

But this is much higher than the loss of efficiency caused by the additional weight. In addion the hybrid drive, allows the ice to stay in a more efficient range also making up for the weight. A big battery is needed for much acceleration help, which is why vw chose that 5kwh beast instead of something lighter like a 0.8kwh lithium used in some german hybrids. Super caps + a smaller battery might make sense in the future.

Agree here, but without expensive materials like carbon fiber, you can't drop much below 2500 lbs. That efficient xl1 in aluminum would weigh 2000lbs and is a very small 2 seater. Shrink the liftback to prius c size, but use all the tricks but go less expensive aluminum instead of cf, you might get to 2300lbs but I don't think we will go there.

 

You got that right.

 

Just recently rode in an old Mustang fastback that also had a huge rear window. I would love it, if the engineers can make the thinner supports strong enough for the "steel cage" safety effect.
My wife, on the other hand, thinks the Pacer was one of history's ugliest cars.

 

I have to agree with your wife. The upside down bathtub design also has a cd of 0.43 and its width means it has a large frontal area. I guess it was good drag for the 70s, but awful design for the current decade. You can get good rear visibility without going through that shape.
1978 AMC Pacer - The 50 Worst Cars of All Time - TIME

 

Fiat 500 meets its ancestor!

 

I don't mean recreate the shape of the Pacer--just see if you can increase the amount of glass back there you can see through, if you can do it without compromising body integrity in rollovers.

 

most exciting thing about this "news" is that it reminded me how new G4 will come out within next 14-15 months

 

This thread started the same day I received an unsolicited card from the dealer I repair my 07 saying that they want to give me an aggressive pricing deal that will please me, even if I don't buy it from them. They said they "need" them.

 

VW has several variations of this 1 liter prototype - So please pardon my asynchronous learning patterns ...

Europe seems to have this love affair with diesel which I have a hard time understanding why. Maybe it's a American mind-thought thingy? I would have opted for a gasoline rather than a diesel plug in hybrid for the USA since gas is more accessible in the USA than diesel. Still -if the VW XL1 does make it stateside next year -I'm sure it will be a hit among the North American hypermilers because it looks soooo much like the 1st gen Honda Insight. However, one thing I can't tell from the wiki entry is whether a driver can shut down and restart the XL1 diesel engine on the fly(while the car is in motion) or whether the car does this thing automatically for the driver; this is a critical characteristic of the 1st gen Honda Insight which allows a hypermiling technique called NICE ( the Prius can do this automatically in with its stop-start idle tech or the driver can manually induce it via the accelerator action) - it is also one of the reasons hypermilers can do +100 mpg on the 1st gen Honda Insight. I do have doubts about the market acceptance of the VW XL1 narrower staggered two seating arrangement (but not completely behind each other) as oppose to the original Honda Insight's wider tandem(side-by-side) two seater arrangement. I suppose its worth the gamble though.


It's not the electric motor or the size of the battery per se that affect the hybrid's fuel efficiency but the max current load of its battery system. NiMH can't sustain a high enough current load to have a wide enough electric motor speed range over a wide enough ascend/uphill climbing driving scenarios to boost the MPG any further - which is where Lithium ion battery's higher current load comes into play. A Lithium ion battery pack can expands the electric motor's range for assisting the ICE-- hence we see Li-Ion based hybrids like the Ford C-max get better MPG than NiMH based hybrids of similar configurations like the Prius v despite the fact that the Ford C-Max is a heavier car. If you swap the Prius v NiMH pack for a Lithium ion pack - because the Prius v is a lighter car - its EPA rating would shoot past the Ford C-Max's. I agree super caps would help boost a smaller battery's current load capacity for short burst (if the super caps have a very high temporary amp rating) and if implement correctly could probably help increase MPGs -- I am not sure but I am guessing that IP barriers is slowing down this hybrid evolutionary pathway/implementation.

Rolling resistance is the more significant energy sucking factor in speeds less than 40 mph. For most vehicles - wind resistance is the more significant energy use factor at about 45 to 55 mph. For trucks and mini-vans, wind resistance is more signifcant energy use factor at about 25 to 35 mph. Within the speed range of 40 mph to 60 mph for most non truck vehicles, vehicle design can shifts the tipping point between rolling resistance and aerodynamic drag - reducing the energy requirements for a given speed. For example, a two wheel human powered vehicles(HPV), e.g. a canopy bicycle racer, has been recorded going as fast as 60 mph on a flat smooth asphalt road ( the athlete powering this vehicle is generates approximately 1 hp).

 

This may be a bit off topic, but what happened to the hybrid small pickup concep?, I think it was called the BAT-AT. That would be a nice addition to the Prius line.


iPad ? HD

 

It was A-BAT. Toyota and Ford are working together on a full hybrid system for pickup truck. Something should come out soon.

 

Totally agree...especially if it can tow small/light trailers.

 

Get the 4WD version in 2015.