Yes, that MPG figure is nonsense.
Running on generator power I get about 45mpg at 70mph on the motorway, rising to 50mpg if I drive below 60mph.
Electric Car Charger
- Thread starter scarboroughmonkey
- Start date
Yes, that MPG figure is nonsense.
Running on generator power I get about 45mpg at 70mph on the motorway, rising to 50mpg if I drive below 60mph.
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There are some people who take the building of hi-tech soap box carts very seriously, have competitions etc, and they use flywheels for braking - rather than throw away kinetic energy when you need to slow down for a bend, store it in the flywheel and then release it on the straight.
The rules for calculating mpg are given in a European Directive (yes, more EU greenwash) that assumes most of the journeys are within the range achievable on the batteries.
You can get those sorts of figures from "mechanical" cars if you're careful - I would have thought that the engine in yours would do better, as it can be run at a constant speed at its most efficient setting.
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I drive a VW Jetta 1.6 Bluemotion, and get around 80 mpg on a run in warm weather. Overall average is over 70 mpg. Admittedsly I drive quite slowly, and most of my mileage is on motorways, but even in a hurry I can get 60+ mpg. I've checked the trip computer against the actual consumption and it's pretty well spot on.
The problem with the Ampera is that the energy in the fuel is being transformed to electrical energy then into mechanical energy, so you don't gain as much as you'd think by running the engine close to maximum efficiency.
Which in my case is true - I haven't bought any petrol since Christmas and the tank is still 2/3 full.
Sooner or later some rapacious chancellor will start taxing electricity used to charge electric cars at the same levels as hydrocarbon fuels. Maybe LPG initially, but I'm surprised that that has remained as low as it has.
Yes, I agree that sooner or later that will happen. But I don't think it will happen until there are enough electric cars on the road to make it worthwhile.
Currently, they are looking at how to increase take-up of EVs. I've had several interviews with various research companies working for the DOT, looking at this. At the moment the cost of the batteries means there is a significant price premium on EVs and I think that will have to come down before they become commonplace.
I find the fuel consumption figures quite interesting, generally talking of 45 - 50 mpg for modern engines. The best fuel consumption I achieved on normal motoring was 60mpg at 70mph motorway, 60 if I was naughty and did 80 mph and 55 town work. The car? An L reg Montego Diesel Countryman with a Perkins 2litre engine, and that was carrying full loads. It had to go when the engine died at 350,000 miles.
Do these rules attempt to calculate, and include, a notional 'petrol usage' figure for the generation of electricity used to charge the batteries?
If not, as Eric has pointed out, the closer one gets to the situation in which all journeys are 'battery only', the closer will the apparent mpg (miles driven divided by petrol put into car) get to infinity!
Kind Regards, John
Yes, I'm sure they would like to do that, and I've often seen it discussed. However, whilst it would obviously be easy to do for 'public charging' facilities, it's hard to see how it could be implemented (in a manner which was not easily circumnavigated) for 'home charging'.
Kind Regards, John
Don't be silly John, that would be much too rational! Next you'll want the claims for carbon reduction to consider the energy/carbon used to make the batteries.
Yes, my question was almost rhetorical
. However, I don't think it's me being silly and, even given what the manufacturers (and proponents of EVs) would like, I'surprised that an EU directive can be such as to be so 'silly' and potentially misleading. If, as you said, the rule relates to situations in which most journeys are 'battery only' then one can get almost any answer (mpg) one wants (up to, and including, infinity), depending on what number of 'petrol miles' is assumed - hardly useful to motorists!Kind Regards, John
I agree in general. However the point of the directives is that all cars using a similar power source have a common set of rules for quoted fuel mileage, so the benefit to the motorist is not really about comparing EVs with internal combustion, but more about comparing EVs with each other. Perhaps they should also include a "miles per kilowatt-hour" figure.
Remember that EU Directives are written by EU staff following advice from lobbyists, rather than by transport engineers. They are already "unfair", in that the method of measuring exhaust emissions is much more benign for diesel engines than for petrol, and the emissions from LPG don't take account of the small amount of LPG that is emitted when disconnecting the pump nozzle from the car.
Remember that EU Directives are written by EU staff following advice from lobbyists, rather than by transport engineers. They are already "unfair", in that the method of measuring exhaust emissions is much more benign for diesel engines than for petrol, and the emissions from LPG don't take account of the small amount of LPG that is emitted when disconnecting the pump nozzle from the car.
Recording devices in vehicles.
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