X
Xage
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- #31
yes yes yes and now to satisfy my curiosity how the hell does 1 calculate from mph to kph?
C
Cdr
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- #32
1 kph = 0.621371192 mph
Apparently....
Apparently....
T
Tom
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- #33
half your mph added to your actual mph = rough kph
eg
50mph + 25mph = 75kph
eg
50mph + 25mph = 75kph
L
leggy
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- #35
mph = 1.6 * kph
T
throdgrain
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- #36
It is 56 mph m8, they do tests for fuel efficiency, an urban cycle at 30 or so and a "open road" one at 56.
Having said that, in modern cars I would imagine 56 and 70 are quite close in terms of economy.
T
Tom
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- #37
That depends on the amount of drag, which varies between models of cars.
J
Jonaldo
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- #38
Never had anyone in drag in my car fyi 
I'm from Essex where men dress like men and women dress very skimpily indeeeeeed.
I'm from Essex where men dress like men and women dress very skimpily indeeeeeed.
B
Big G
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- #39
yes, it's ~55 mph for optimal miles per gallon.
Obviously, not in second gear doing 6500 rpm
, but probably in top gear.
G
Obviously, not in second gear doing 6500 rpm
, but probably in top gear.G
J
Jupitus
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- #40
I always do 55 in 2nd gear... what's wrong with me???
E
Embattle
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- #41
200 MPH
O
old.ignus
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- #42
Are you all making this up?
You talking about how manufacturers calculate their miles per gallon, this is in test conditions remember. If you're driving along at say 50mph you maybe getting their faster than if you were doing 40mph, but what happens if you have to slow down for a corner or whatever, down to 40mph that's 10mph worth of fuel cancelled out by the brake.
Also you have to consider that the engine also serves as a generator, the more power you draw from it the more fuel it needs so heater and stereo off, fans off, using cruise control would probably drain it too.
Then you want a high gear for low revs and take it steady so that you don't have to use the brake as often, engine breaking counts for this too. You're looking for a constant speed.
Also remember that the fuel is pumped from one side of the tank so when cornering or speeding up/slowing down or when you're on a slope the fuel guage could be wrong.
And here's a tasty fact for you, only approximately 25% of the petrol used in a petrol engine is producing power, whereas approximately 35% of the diesel used in a diesel engine is producing power.
You talking about how manufacturers calculate their miles per gallon, this is in test conditions remember. If you're driving along at say 50mph you maybe getting their faster than if you were doing 40mph, but what happens if you have to slow down for a corner or whatever, down to 40mph that's 10mph worth of fuel cancelled out by the brake.
Also you have to consider that the engine also serves as a generator, the more power you draw from it the more fuel it needs so heater and stereo off, fans off, using cruise control would probably drain it too.
Then you want a high gear for low revs and take it steady so that you don't have to use the brake as often, engine breaking counts for this too. You're looking for a constant speed.
Also remember that the fuel is pumped from one side of the tank so when cornering or speeding up/slowing down or when you're on a slope the fuel guage could be wrong.
And here's a tasty fact for you, only approximately 25% of the petrol used in a petrol engine is producing power, whereas approximately 35% of the diesel used in a diesel engine is producing power.
B
Big G
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- #43
Generally, the optimal speed is ~55 mph.
/me switches repeat off
/me switches repeat off
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old.ignus
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- #44
only in an ideal world.
T
Tom
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- #45
My gauge works by measuring the vacuum in the tank, therefore that isn't a problem
B
Big G
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- #46
Hence why i said "generally" and "circa", because obviously there are other factors that come into play.
You could be incredibly pedantic and say "only in an ideal world, where that world is completely flat, and that if you were to go up a slight incline, the mpg would drop, or if you were driving into the wind" blah blah.
You could be incredibly pedantic and say "only in an ideal world, where that world is completely flat, and that if you were to go up a slight incline, the mpg would drop, or if you were driving into the wind" blah blah.
S
Shocko
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- #47
That's interesting... Assuming that 100% of the fuel is ignited, how is that possible? The bigger the explosion, the more force there is, the greater the power... I just don't see how what you've said can be true.
T
Testin da Cable
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- #48
it means 75% of petrol burnt is doing nothing more than screwing up the environment
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leggy
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- #49
A lot of the energy is dissipated as heat. In actual fact I dont even think a 4 stroke internal combustion engine is even 25% efficient. I'm sure it's a lot less.
/edit 75% isn't screwing up the environment. This is just a figure for power loss due to heat and various other loss factors.
/edit 75% isn't screwing up the environment. This is just a figure for power loss due to heat and various other loss factors.
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Testin da Cable
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- #50
I know tbh I have no idea at all what the ecology-buggering output is of the average pertol engine. on the other hand I read somewhere (iirc) that a good diesel can get you about 40% effieciency
tbh I have no idea at all what the ecology-buggering output is of the average pertol engine. on the other hand I read somewhere (iirc) that a good diesel can get you about 40% effieciency
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leggy
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- #51
I know that you knew. I just didn't know if you knew that I was joking about you not knowing.
T
Testin da Cable
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- #52
not knowing that I knew? I'm confused now Leggy. When I'm confused I don't function properly
D
dysfunction
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- #53
That used to be the case. Now every state can decide on their own speed limits.
Quite a few of the states have increased the speed limit to 70mph.
And NO they dont use KPH. They are just as backward as the UK is in that respect.
R
r32
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- #54
And here's a tasty fact for you. 99% of diesel cars are inherently more shit than their petrol counterparts, thanks to the Massey Ferguson effect and the paltry 2000rpm power band.
Oh and its 56mph. No "ummm ahhh it depends" horseshit. It's 56mph. End of discussion.
A
Any
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- #55
Imperial for life!
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old.ignus
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- #56
steam power was only something like 15% efficient you know. One of the things I remember from my motor vehicle repair course at college.
end of discussion my arse. 55mph if you want to get somewhere faster, I bet if you put the car in first and just ran on tick over you'd probably get better mileage but it'd take forever. I believe that's the method used by the men in that competition where they have to travel the furthest on one litre of petrol.
end of discussion my arse. 55mph if you want to get somewhere faster, I bet if you put the car in first and just ran on tick over you'd probably get better mileage but it'd take forever. I believe that's the method used by the men in that competition where they have to travel the furthest on one litre of petrol.
T
Tom
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- #57
I think you'll find thats total bollocks tbh. Drive the new V10 Diesel in a Phaeton if you disagree. Also, my paltry 1.9Tdi will outperform most 2 litre petrol engines in most respects.
And the R32 is a bag of overpriced shite.
B
Big G
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- #58
I agree with Tom, the new common rail diesels are fapping rapid, with the ford TDCi's and Audi, Golf & Passat TDi's being every bit as fast as the equivalent petrol engines with much better mpg than the petrol.
Additionally, they have mountains of torque and pull from low revs, so the TDi's are quicker 30 - 70 in 4th gear than a petrol - fantastic on a motorway.
less than 9 secs to 60 (for a diesel), "more torque than a porsche boxter" and 42 mpg.
Yes please?
G
Additionally, they have mountains of torque and pull from low revs, so the TDi's are quicker 30 - 70 in 4th gear than a petrol - fantastic on a motorway.
less than 9 secs to 60 (for a diesel), "more torque than a porsche boxter" and 42 mpg.
Yes please?
G
E
Embattle
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- #59
I think my old man managed nearly 50mpg in his BMW diesel and like other modern diesel it is fairly fast.
R
r32
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- #60
Diesels still have a long way to come before I would consider buying one. I had a test drive in a BMW 320d before I bought my R32 after a friend suggested it. Great car, great engine (for a diesel). Would I buy one? No. Not a chance. Sure it was rapid enough, but 9 seconds to 60 is still a long way away from 6. It loped along on a wave of torque well enough, but when you really wanted to wring its neck, it went into a sulk as soon as you reached 4000rpm. Call me old fashioned but this is when a performance car should just be coming on song and the speedo needle should take off at around this point. It certainly shouldn't require a change of gear. Kinda defeats the object of masses of lazy torque imo. It should take the effort out of driving, not put it back in.
Face it, if diesels weren't more economical no one would buy one. As you can no doubt tell from my choice of car (which is not a bag of overpriced shite out of interest. 22K for a Golf with a 3.2 litre V6, 4WD and the best handling in its class bar none - don't argue with me about this, argue with evo, I just agree with them. Sounds like a bargain to me), economy was pretty low on my shortlist (it was right below crash safety and number of airbags on my list), so the only point in buying a rattle and smoke box was pretty much negated.
Two issues with diesel power need to be addressed before i will go near one:-
1) The rev limiter. If it can't go past 5000rpm its not an engine imo.
2) The noise. The latest round of diesels do sound much better, but even the best (I'm thinking BMW here, none of this two 5cyl engines fused together pish which VW seem to think is the way forwards for the Touareg) simply cannot match the best in the petrol field. When you've heard a Honda VTEC screaming for the red line, an Alfa Twin Spark howling through the midrange or a BMW straight six creaming its way through the rev range, I'm sorry but the chiga-chiga-chiga of a diesel just doesn't even remotely compare.
Oh and ignus, your theory about going slowly doesn't work. Ever been in a traffic jam? Even the ones aren't start-stop result in cained fuel consumption figures. Just to make sure I tested your theory on a backroad last night. I tried varius speeds up to 80, and reset the mpg computer each time. The result? The highest mpg figures (36.6 if you're interested) occured at................
56mph.
In a word, 0wned.
Face it, if diesels weren't more economical no one would buy one. As you can no doubt tell from my choice of car (which is not a bag of overpriced shite out of interest. 22K for a Golf with a 3.2 litre V6, 4WD and the best handling in its class bar none - don't argue with me about this, argue with evo, I just agree with them. Sounds like a bargain to me), economy was pretty low on my shortlist (it was right below crash safety and number of airbags on my list), so the only point in buying a rattle and smoke box was pretty much negated.
Two issues with diesel power need to be addressed before i will go near one:-
1) The rev limiter. If it can't go past 5000rpm its not an engine imo.
2) The noise. The latest round of diesels do sound much better, but even the best (I'm thinking BMW here, none of this two 5cyl engines fused together pish which VW seem to think is the way forwards for the Touareg) simply cannot match the best in the petrol field. When you've heard a Honda VTEC screaming for the red line, an Alfa Twin Spark howling through the midrange or a BMW straight six creaming its way through the rev range, I'm sorry but the chiga-chiga-chiga of a diesel just doesn't even remotely compare.
Oh and ignus, your theory about going slowly doesn't work. Ever been in a traffic jam? Even the ones aren't start-stop result in cained fuel consumption figures. Just to make sure I tested your theory on a backroad last night. I tried varius speeds up to 80, and reset the mpg computer each time. The result? The highest mpg figures (36.6 if you're interested) occured at................
56mph.
In a word, 0wned.