General > General Technical Chat
Confused about PHEV, Hybrids, etc...
emece67:
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tom66:
--- Quote from: emece67 on July 30, 2022, 08:44:58 am ---The energy needed to move a car depends primarily on:
* front area
* Cx
* speed
* mass
--- End quote ---
Yes. And a lot of this is down to the relatively new obsession with SUVs. They have a place for people with large families, but the majority of people would be absolutely fine with a small to medium hatchback car, or an estate, which all have better aerodynamic profiles due to the small frontal profile and lower road position, and usually they weigh less.
nctnico:
--- Quote from: gnuarm on July 30, 2022, 04:00:18 am ---
--- Quote from: nctnico on July 28, 2022, 07:29:11 pm ---If you look closely at the animation in this video from Toyota, you'll notice that the length of the strokes is different:
https://sherbrooketoyota.ca/en/videos/atkinson-cycle-engine So it looks like Toyota is doing more than just having different valve timing.
--- End quote ---
Sorry, I don't see that and they don't talk about it.
--- End quote ---
I put the mouse pointer at the lowest point and at some point the piston doesn't reach it. But this could be an animation effect / artefact. Bottom line is that I have not been able to find whether Toyota Atkinson engines do or do not have different stroke lengths. I don't want to get into the mechnanical details; if Toyota uses it they probably found a clever way of doing this.
NiHaoMike:
--- Quote from: tom66 on July 30, 2022, 08:48:56 am ---Yes. And a lot of this is down to the relatively new obsession with SUVs. They have a place for people with large families, but the majority of people would be absolutely fine with a small to medium hatchback car, or an estate, which all have better aerodynamic profiles due to the small frontal profile and lower road position, and usually they weigh less.
--- End quote ---
Big cars don't have to be inefficient. The new Sienna gets 36 MPG - better than some sedans!
https://www.toyota.com/sienna/
The EPA really should tighten up efficiency requirements. Toyota showed what's possible, no excuse for automakers to keep cutting corners.
gnuarm:
--- Quote from: emece67 on July 30, 2022, 08:44:58 am ---The energy needed to move a car depends primarily on:
* front area
* Cx
* speed
* mass
I see car manufacturers selling progressively bigger, faster and heavier vehicles, but trying to convince us that they are doing all technically possible to enhance fuel economy by 1 % putting into it more and more technology, but not touching, in fact worsening, any of the main factors.
--- End quote ---
There have always been plenty of small cars to buy, and this will always continue. If you can't find a small car, that's on you.
--- Quote ---The previous Toyota video is interesting. One of the cars appearing on it has a front area well above 2 m2, a Cx ~ 0.4, a mass above 2 ton and a top speed ~170 kph, but they are showing us the benefits of its Atkinson capable engine to get a fuel economy of 8.8 l/100 km. It is plainly obscene, the last car I owned with such a poor fuel economy was build/bought in the early 80's.
--- End quote ---
Car makers have to sell the vehicles people want to buy. Otherwise they become another Hudson or Studebaker.
--- Quote ---Car manufacturers deserve heavy regulations limiting the amount of energy their cars can use, or banish.
--- End quote ---
How about we simply put the responsibility on the people buying the cars. How about a tax on gross vehicle weight and/or frontal area, or even just increase the fuel taxes? A fuel tax gets right to the heart of the matter. To make it less regressive, we can offer a income tax credit for the first 280 gal (14,000 miles at 50 mpg). So buying a car with worse mileage than 50 mpg or driving more than 14,000 miles, incurs the tax. It also equates to a credit to drive less than 14,000 miles or getting better than 50 mpg.
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