Petrol Consumption

[Thrower]

I`ve read that it increases a vehicles petrol consumption if you run it with headlights on, as in daytime driving, which has been proposed by some agency study group.

Is this true, as I can`t see that it does, but maybe I`m missing something? (apart from intelligence I mean!)

[TWR]

On the six o clock news tonight, The goverment has just passed a law against anyone farting in public, I have heard some Bull in my life but this takes the bloody tkt, whilst there's pedos out there messing up kids lifes and some dick head comes out with garbage like this. Is this Britain? or is it loony country?

[sir.knobby]

I bet thrower is the sort of person who cant get his head around drivng at 50mph uses less fuel than driving at 70mph.

His argument being that you will get to your destination faster if you drive at 70mph therefor you will not be driving for so long so if you arrive at your destination half an hour earlier by doing 70mph instead of 50mph then that last half hour you will be not using any fuel.

If you see what I mean

[topogigo]

Take a look at this, If you know Kip Kay, you will not be surprised that he does this, the guy is brilliant.

http://kipkay.com/

[TWR]

Thrower, car consumption can be increased by correct Tyres/Pressures, Load, servicing, windows (Up) No roof racks, Style, Types of wheels eg/Alloy / metal, Weight. type of fuel.

[bigboots]

Your all missing the big question here WHO is paying for these surveys? us no doubt through some sort of taxation

[Thrower]

Sir Knobby,

No I`m not that sort of person at all, I don`t know how you managed that leap of logic with the sort of thoughts you seem to have. You didn`t however manage to contribute to the question.

TWR. I think you may mean car (petrol) consumption can be decreased (not increased) by your methods, which are by the way, pretty obvious, but perhaps you didn`t read the question.

Anyway, it seems the general opinion is that it would save about 1% per year, or in my case about �15. This of course would mean the Government may have about �2 less of mine to waste. (ANY Government).

So, on balance, I`ll keep my lights off.

[ABerrant]

I would like to revisit jake-the-peg's power calculation.

DRL does not mean running on sidelights. If/when it becomes mandatory, cars will be either be;

manufactured/retro-fitted with DRLs i.e. 42W (2 x 21W)

or

for the majority(?) of vehicles, required to run with dipped beam headlights i.e. 160W (2 x 55W + associated illumination e.g. rear lamps, reg plate lamp, dashboard lamps etc.).

Also the prevalent automotive alternators of the Lundell (claw pole rotor) type tend to exhibit an efficiency range more like 45%-65% (dependent on speed and load). TRL notes the EC study assuming a 50% efficiency - let us use 60%.

So...

160W = 0.215hp

@60% efficiency = 0.358hp loading

The mechanical power needed to maintain a car at 60mph on level ground against a 10mph headwind is of the order 20hp (dependent on drag coefficient, rolling resistance, gear ratio etc.) - even if we add an exhorbitant 100% for incidentals (inefficiency of engine and drivetrain, use of electrics other than headlights, bouts of acceleration etc.) we reach a figure of 40hp for average power drawn from the engine.

0.358hp expressed as 1% of 40hp appears to fit within TRL's conclusion of the figure being of "reasonable accuracy".

Nice try though.