There is something about this 110 MPG car that does not smell right | Hacker News Reader

There is something about this 110 MPG car that does not smell right

blogs.howstuffworks.com

58 pointsadg20 comments

A lot of it seems to be tricky math. It's not MPG, it's MPGe, the 'e' is for 'equivalent'. However, marketing guys have been playing those games forever, so no surprises there.

They're claiming E85 has 1/3rd less energy than gas, so they're actually getting 110*0.66 = 72.5 mpg of E85.

72.5 mpg is not as good for marketing hype, but it's still impressive.

He seems to be playing some games with the acceleration profile as well. If you 'gun it', you're in 'power mode', not 'efficiency mode', so the mpg numbers no longer apply. I'm not certain if this is common practice or not in these kinds of tests. It probably is.

I think he is mainly just taking control of the throttle away from the driver, and doing a "throttle by wire' system, giving you the most efficient (and probably painfully unresponsive) acceleration profile possible, when you're in 'efficiency mode'. I'm not sure if that buys him the whole 72.5mpg or not, but it's in his toolbox. <EDIT: Actually I can imagine such a system that wouldn't be too bad. When the user makes relatively small acceleration addition requests with the throttle pedal, you use your efficiency optimized acceleration profile to give it to him. When the user "stomps on it", because a truck is about to hit him, then you give him the requested throttle amount. I can imagine such a system would yield efficiency gains without being too painful to drive.</EDIT>

Whether there's something else in the engine that gives you the rest of the efficiency gains, or if that's all of it, remains to be seen.

Of course, we don't know if any of this is real, but if it is, it's a cross between "real" and "marketing real".

my idea of a fuel-efficient car only has a brake pedal - acceleration is controlled by a computer

People want to be able to floor it to merge into traffic - its a safety feature.

If they actually have 312k orders (his 10 staff will be busy! http://www.toledoonthemove.com/news/news_story.aspx?id=31787... ) then I'd expect someone tested the engine first? Either way they've gone into production - if it's all marketing then we'll know in a couple of months.

Comment #1 below really says it: Even if you have a 100% efficient engine, it takes more energy to propel that un-aerodynamic Mustang through the air 1 mile at highway speeds than you get out of 1/100 gallon of gas. And that's ignoring rolling friction and powertrain losses. It's a perpetual motion machine.

I think what they need to do is make an instant on/off engine mated to an instant on/off transmission.

Right now, even when you are going down hill, the car slows down because of transmission friction, and you end up hitting the accelerator to maintain your speed.

If it's instant on/off, they can afford to let the car go in neutral when the driver isn't accelerating, so you won't use up fuel fighting the transmission. Same goes for instant on/off engine. If it can be turned on instantly, there is no reason to keep the engine running when you are just rolling along

well they kinda do that with the prius, the motor will start up when needed using the high speed wheel motor which can start the engine much more easily than a starter motor.

I think the simpler route is to just use an electric motor for the power directly mated to the wheels. No drivetrain, it's only used when you need power (no idling) and it's instant on/off....

At highway speeds, it's mostly aerodynamics, so it won't buy you that much.

Check out this entry in the Tesla Motors blog: http://www.teslamotors.com/blog4/?p=70 It talks about the power required to maintain a certain speed and what's responsible for it.

The Tesla Roadster uses ~ 230Wh/mile to cruise at 55mph. What is that in equivalent mpg? Gas has 34MH/liter, which is 35800 Wh/gallon. For reference, that gives 35800/230=155 mpg.

With the given frontal area and Cd of that Mustang, it takes 140Wh/mile to overcome aerodynamic drag only. Let's assume they have a magic, loss-free power train. That leaves the tire drag, which should be about the same as the Tesla since they are both high-performance cars and probably weighs the same given the Tesla is dragging around all the batteries. The Tesla plot shows tire drag to be ~60Wh/mile, which adds up to a theoretical minimum of 200Wh/mile, which is 180mpg.

A more realistic assumption is that the Mustang power train (they only talk about engine so I assume it has a standard transmission) is no more efficient than the Tesla's, which requires a further 75Wh/mile. This brings us to 275Wh/mile, which is 130mpg.

To reach 110mpg, the engine would thus need a thermodynamic efficiency of 85%. This is more than twice the efficiency of diesel engines at ~40%.

It can't work.

110 miles / gallon = 2.14 liters / 100 km

My suspicion is that they're not counting the ethanol in their MPGe calculation. They claim to be using E85. In other words, the fuel mixture may contain about 85% ethanol. Their MPGe calculation probably only counts the gasoline in that mixture, the 15%.

From their website:

"A Northwest Ohio start-up company is nearly ready to create 2,000 green auto industry jobs!" [1]

They've received 312,000 orders ... right. For comparison the tesla model S has received over 1,000 orders [2]. An order of magnitude difference. Why haven't we already heard of these guys?

1. hp2g.com/articles.html; 2. www.autobloggreen.com/2009/05/12/tesla-reports-over-1-000-model-s-orders/

Because everyone here is focused on Silicon Valley, and Tesla hangs around there.

For perspective, the new Prius model has a sales target of 100,000 cars in 2009.

Somehow I doubt that some small company with a new engine technology has outsold threefold Toyota's massively efficient and effective sales, marketing, and dealership network across the US, and gone completely unnoticed by mainstream media.

The car business involves a lot more than just the design of the engine or the car.

I think the trick is the "equivalent" part. If I got it right, they are using some sort of fuel which provides 1/3 of the energy regular gasoline does. Which means they are probably doing 110/3 mpg on this type of fuel.

That may be true, but it still sounds a bit insane. This is orders of power better than conventional results.

It doesn't matter what the fuel is. You get the same amount of energy out of it, so it's no easier running 110*3/2 mpg on E85 (which is 2/3 the energy density) than 110mpg on gas.

its probably gets 110mpg based on the % of fuel that is gasoline. ie the fuel is 99% ethanol and 1% gas so the car runs a regular 20mpg but because only 1% of that fuel is gas it gets a magical 2000mpg (20/1%). Their probably doing something shifty like counting the ethanol as free energy and therefore not including the ethanol burned in their MPG calcs...

A car that does 377 mpg: http://www.seattlepi.com/local/351903_needle20.html

But that means: hardly any chassis, no gearbox, aircraft tires, the engine is wrapped in asbestos, driving a constant 30 mph, etc., etc.

This car is in the Guiness book of records.

Edit: BTW, I'm not claiming that means the car in this article is also plausible: if it claims to yield a constant 55 hp, then it can't do 110 mpg.

I think this one is where things will have to go if we want efficency: http://www.aptera.com

Or this one for 230mpg

http://en.wikipedia.org/wiki/Volkswagen_1-litre_car

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