Gas only mpg

Zero.

 

How can we answer the question if the premise is impossible?

 

If the electric engine/motor isn't working, then the car can't start the Internal Combustion Engine (ICE).

Ok, so let's pretend that you get the ICE started and then the electric engine/motor stops working. In that case, the transmission won't work, because the ICE can't supply power to the wheels if the electric motor can't supply an opposing force to the Power Split Device (PSD). So still the car won't move.

Ok, so let's suppose you get the ICE started, and then you find a way to immobolize the the sun gear in the PSD. Now you've got the problem of only having one gear and no clutch. The ICE will die as soon as you stop the car. When you try to accelerate from very low speeds, the car will really struggle, and at high speeds you'll be redlining the ICE.

Since you can't use the electric engine/motors at all regenerative braking is useless, and since you can't restart the ICE, turning it off when slowing down or stopped is useless. At this point you might as well throw a clutch and manual transmission in there.

Ok, now that you have a way to switch gears and to stop the car without killing the engine, you'll need to throw a starter motor in there. You really don't want the excessive wear and tear on the starter motor and the ICE the you'll get from trying to restart it unnecessarily under such conditions, so the engine will idle whenever the car is stopped or the transmission is in neutral.

Now since you don't have the two powerful electric motors to give you the boost in power you need for acceleration and hill climbing, the car will be almost undriveable. 76hp in a 3,000lb car just won't cut it. You'll have to modify the valve timing to act as an otto cycle engine instead of an atkinson cycle. This will give you the power you need to actually drive the car.

Ok, now just go look at the MPG rating of any modern 3,000lb manual transmission otto cycle 4 cylinder 1.5L engine car. You'll have a pretty good approximation of what this frankenstein Prius would get. You really couldn't call it a Prius anymore though could you. You'd probably call it a large heavy Yaris.

In that case, since the Yaris gets about 29city/35hwy but only weighs about 2300lbs, I'd predict you'd get about 27city and 32hwy.

 

It is a "gas only" car, what other energy goes into the car?

Most of the efficiency is in the engine, at about 40% efficient it is about double a conventional engine. The electric motors just allow it to be in a car with good acceleration. If you put the Prius engine in say a Yaris manual it would be pretty economical but very gutless I imagine.

 

And what would the mpg be if the ICE never ran?

 

I bet Darell will be glad to tell us!

 

I think it's called the now-defunk Echo. Remove HSD and ta-da, you've got it...mostly. Prius share(ed) the block of the Echo, but that's about it. Prius is tuned for an Atkinson-Miller cycle not the standard Otto-cycle Echo. Echo would be lighter in weight, smaller in size than Prius. Echo MPG was not quite 40? Maybe 38 combined? And emissions would be higher in the Echo.

would the new Yaris contain the same drivetrain as the Echo?

Overall, it's a tough compare since the Prius has EVERYTHING integrated to improve all aspects of efficiency.

 

Think of it a different way. Steady-state on the highway, the
HSD is basically used as a transmission because there's very
little battery current in or out. So the "hybridness" isn't a
factor in that situation. Under those circumstances, that little
mill is good for substantially over 50 MPG -- over 60 in nice
weather, as detailed in several of my trip-log writeups. By
itself it's very efficient, and pretty much right in its sweet
spot when you're just tooling merrily along the interstate.
.
_H*

 

no direct comparisons can be made with any car on the road. similarities in engines, vehicle weights, and HP will mean nothing because there is no way to determine how the changes in the CVT, atkinson cycle, etc play a part.

even a yaris must provide higher low speed torque which kills efficiency. the big reason why a Prius gets better gas mileage is...

NO!!! it has nothing to do with the power stored in the battery... at least not directly. all the power still comes from the gas engine, but because of EV operation and assist at low speeds or other high torque applications, this allows the gas engine to run AT ITS MAXIMUM EFFICIENCY NEARLY ALL THE TIME.

that is the reason why you get better gas mileage.

so its my contention that with all things equal , your mileage might be 5-10% lower if for some reason the battery pack died...this assumes that you are moving at highway speeds on flat ground simply because on its own, the engine does not have enough power to accelerate the car

and yes, that is a BIG "if"

 

Interesting question. And as the replys reflect...depends.

As pointed out, in its steady-state sweet spot, it's quite efficient with remarkable gas mileage.

But as the cars sole power source, it's quite undersized and when loaded with the hill climbing, accelerating responsibilites of full-time, everyday duty,
I think it would return quite poor overall results. 30MPG ?
Because it would be working outside it's sweetspot.

My inlaw's Crown Vic probably gets 40 MPG on the highway, in it's sweet spot.. maybe.

 

Greetings -

I can tell you with a relative degree of certain guesswork. I owned an Echo a few years ago and in Summer would get 48 regularly in my commute - it was a 5 speed. In the winter, however, I would be down around 35.

Now I have the Prius and for the past week it has been extremely cold here and I always leave the 'consumption' screen on. I only have two stops on my way to work and the engine will only turn off on one out of every 6 or 7 stops. So over the past 300 miles I've average 36.6 mpg - mostly highway. Of course you can't calculate the regenerative braking benefit, but being realistic, It probably only gives you a couple mpg. The Prius does get a decent benefit from coasting though and my drive is hilly so I'm sure I'm getting another few mpg out of that. Then consider the Echo was lighter but the Prius is more aerodynamic. I don't know how a 5sp tranny compares to a CVT but I'll bet they are similiar if you drive a stick the way I did.

So, all that considered - The Echo got 48 in the summer, so my 'guess' would be the Prius would get mabey close to 40 on the highway in the summer and probably 30ish in the city. And by coincidence, those are the rated mpg's for the non-hybrid 4 door Honda Civic - with a stick, slightly less for the Automatic - which seems to be a somewhat comparable aerodynamic, weight and engine vehicle.

Of course that's 55-60 mph highway and no lead footing stoplights. There are people who can (and do) get lousy mileage in a Prius. But we all know they simply don't know how to drive. I think it was Popular Mechanics that just did a story on Diesel vs. Hybrids and they tag line was Diesels beat hybrids. Of course, they used a VW Polo as their 'comparable' vehicle to the Pruis. PULEESE, I've seen a Polo cold weather testing here in Fairbanks a few years ago, and that thing is tiny! You could almost compare the Jetta Wagon TDI to the Prius - and they are pretty close in mileage and size / weight. That's why I can't wait for a Diesel Prius.

D.