Better Measurement for Fuel Economy

[uppi]

The best measure is CO2 per mile or CO2 per hour. And it should be measured and displayed on the dashboard of all new cars.

And how would you calculate that for electric cars? Would you have to enter the energy mix of your local power supplier beforehand?

 

[Mise]

And how would you calculate that for electric cars? Would you have to enter the energy mix of your local power supplier beforehand?

TBH in this day and age it should be pretty easy to calculate that. Each charging station, including your own home, knows the company it buys its electricity from, and that company knows its CO2 emissions (I'm sure it's a legal requirement in most countries). It wouldn't be hard for the charging station to tell the car what CO2 per KWh (or whatever unit the onboard computer requires to calculate CO2/mile while driving) when it's plugged into it.

 

[Ayatollah So]

Apparently it's more intuitive to think in terms of 10,000 miles (or km) when comparison shopping.

If we told you car A burnt 500 gallons for 10,000 miles, and the other car burnt 555 gal for 10,000 mi, you have an easier time figuring out costs than saying 18 mi/gal or 20 mi/gal

I think I saw that same report. It's because upgrading from 20 mpg to 30 mpg isn't as good as upgrading from 10 mpg to 20 mpg, even though they're both an increase of 10 mpg. So a family with a sedan and a van will upgrade the sedan thinking it's better, when they really should upgrade the van.

Bingo, the correct answer is therefore [units of energy] per [distance]. I.e., gallons per 10,000-mile, or MJ/kilometer, or what have you. And yeah, consumers should get some info that lets them compare energy usage for differently-fueled cars.

 

[uppi]

TBH in this day and age it should be pretty easy to calculate that. Each charging station, including your own home, knows the company it buys its electricity from, and that company knows its CO2 emissions (I'm sure it's a legal requirement in most countries). It wouldn't be hard for the charging station to tell the car what CO2 per KWh (or whatever unit the onboard computer requires to calculate CO2/mile while driving) when it's plugged into it.

But that way there would be no way to compare cars, because the "fuel efficiency" would depend on the charging station. And it would be even more ridiculous in countries that produce all electric energy with renewable energy (e.g. Norway), because the car would always display zero, no matter whether it is a efficent car or the electric equivalent of a gas guzzler.

For cars that produce CO2 themselves, CO2 emission might be a good metric. For all others, it isn't.

The best way to measure efficiency would be something like MJ/km. The only one people care about is €/km (or $/mile or something similar).

 

[Desmond Hawkins]

For one, if we are looking for a new system, it is a great opportunity to get rid of the term "miles".

KM/KWH

 

[Cutlass]

Metric really has never taken hold in the US. It may never.

 

[Desmond Hawkins]

To tell you the truth, Canada is a hybrid at best. No one uses that litres per 100 km crap here. Most people wouldn't know what you are talking about.

We use miles per gallon in every day conversation... although, our gallon might be a bit different, so the numbers are different

We also measure people's heights in imperial and, well, things that can't be mentioned on this forum.

 

[Cutlass]

Well everyone knows Canada is weird

 

[Desmond Hawkins]

We can't help it... we get all of your channels.

 

[uppi]

For one, if we are looking for a new system, it is a great opportunity to get rid of the term "miles".

KM/KWH

But then you have an inverse scale again. kWh/km (or 100km) would be better, if it has to be kWh.

 

[Desmond Hawkins]

Wait, how far would you go under a KWH in an electric car (roughly)?

 

[Mise]

BTW the reason so many CFCers are aware of the inverse of MPG being superior is because there was a thread on CFC not so long ago about it! http://forums.civfanatics.com/showthread.php?t=279590

But that way there would be no way to compare cars, because the "fuel efficiency" would depend on the charging station. And it would be even more ridiculous in countries that produce all electric energy with renewable energy (e.g. Norway), because the car would always display zero, no matter whether it is a efficent car or the electric equivalent of a gas guzzler.

For cars that produce CO2 themselves, CO2 emission might be a good metric. For all others, it isn't.

The best way to measure efficiency would be something like MJ/km. The only one people care about is €/km (or $/mile or something similar).

Ahh, I see your point -- I was thinking from a pollution perspective on a per car-driver basis. There could be several efficiency ratings:

1. CO2 per mile, using national average energy mix for electric cars, to measure the effect of the car on the environment. This rating (actually CO2 grams per km) for petrol and diesel cars is already measured in the UK for each car, and forms the basis of Vehicle Excise Duty (car tax).

2. MJ/km or Energy In / Energy Out over a "typical journey" to measure the efficiency of the engine itself, to compare two electric cars, or two petrol cars.

3. Each car's onboard computer measures (or estimates) the individual car's CO2 or MJ/km or cost/distance etc.

 

[uppi]

Wait, how far would you go under a KWH in an electric car (roughly)?

Assuming a 50 mpg car and double efficiency compared to a conventional car, about 0.75 miles/kWh

@Mise:
Yes, that should work.

 

[Desmond Hawkins]

Miles. So over 1 km/KWH

Either way, you get 1.1ish km / KWH or 0.9ish KWH/KM

How is 90 KWH / 100 km better?

Ya, forget is. Let the Joule people win.

 

[El_Machinae]

Regional dealers could still include CO2/km for advertising purposes. In my region, our powerplant produces .8 kg / kWh