Cars that are economical at 80-90mph? Hypothetically ;)
Discussion
Are there any cars that are economical at 80-90mph (hypothetically speaking, of course!)?
Ok, so this is all hypothetical, as of course no-one goes over 70mph on the UK motorways
But lets just say... a 2004 Seat Leon 1.9TDi diesel FR 150bhp will do 55mpg sat at 70mph and 2000rpm on the motorway.
At 80-90mph the revs are up to 2500-3000rpm and the economy drops to 45mpg.
I understand this is due to the engine being overstrained/revs being higher.
My question is this: would a bigger engine be more economical at these speeds?
Although I guess the problem is that a bigger engine would be less economical in the first place. For example, I know one car with a 3l diesel that will get 42mpg at 70mph. Because this is a 'stronger' engine and higher geared, so you'd still have low revs at 80-90mph, would that then be less affected? I.e. maybe still get 42mpg, or only a tiny fraction less, at those speeds?
If that's the case... perhaps there is an overlap...
I.e. is there a car, with, say, a 2.5l diesel, that gets 50mpg at 70mph. Perhaps this will still get 49/50mpg at 90mph?? So if you were regularly doing those speeds, it would be MORE ecomonical than the 1.9 diesel.
Or is there too many other factors involved - drag, gearing, weight etc.
Even if that's so, in theory, is this logic correct?
Similarly, I might just say f**k it and go for a 2l petrol 'for kicks'. This would get around 35mpg at 70mph. I'm guessing at 90mpg it would get less than 30mpg, lets say, 28mpg.
But if I went for a 2.5l petrol with higher gearing (because, lets face it, a more powerful car with a higher top speed does have higher gearing, so it won't be revving its socks off at 90, right?) that got 33mpg at 70mpg, might it still achieve 31/32mpg at 90mph?
Fingers on the buzzers.... go
Ok, so this is all hypothetical, as of course no-one goes over 70mph on the UK motorways
But lets just say... a 2004 Seat Leon 1.9TDi diesel FR 150bhp will do 55mpg sat at 70mph and 2000rpm on the motorway.
At 80-90mph the revs are up to 2500-3000rpm and the economy drops to 45mpg.
I understand this is due to the engine being overstrained/revs being higher.
My question is this: would a bigger engine be more economical at these speeds?
Although I guess the problem is that a bigger engine would be less economical in the first place. For example, I know one car with a 3l diesel that will get 42mpg at 70mph. Because this is a 'stronger' engine and higher geared, so you'd still have low revs at 80-90mph, would that then be less affected? I.e. maybe still get 42mpg, or only a tiny fraction less, at those speeds?
If that's the case... perhaps there is an overlap...
I.e. is there a car, with, say, a 2.5l diesel, that gets 50mpg at 70mph. Perhaps this will still get 49/50mpg at 90mph?? So if you were regularly doing those speeds, it would be MORE ecomonical than the 1.9 diesel.
Or is there too many other factors involved - drag, gearing, weight etc.
Even if that's so, in theory, is this logic correct?
Similarly, I might just say f**k it and go for a 2l petrol 'for kicks'. This would get around 35mpg at 70mph. I'm guessing at 90mpg it would get less than 30mpg, lets say, 28mpg.
But if I went for a 2.5l petrol with higher gearing (because, lets face it, a more powerful car with a higher top speed does have higher gearing, so it won't be revving its socks off at 90, right?) that got 33mpg at 70mpg, might it still achieve 31/32mpg at 90mph?
Fingers on the buzzers.... go
I started looking into drag coefficient of cars to find the 'slipperiest'
I was surprised to find that some of the cars with the lowest drag (0.26cd) are a Mazda 3 and 'boxy' Mercedes B Class (see this link: http://motorburn.com/2014/01/12-of-the-most-aerody...
My rather chunky Seat Leon 1.9TDi has 0.33cd.
Sooo....
How the hell can a car as 'slippy' looking as the Peugeot RCZ have such a high cd as 0.32/0.33??
I was surprised to find that some of the cars with the lowest drag (0.26cd) are a Mazda 3 and 'boxy' Mercedes B Class (see this link: http://motorburn.com/2014/01/12-of-the-most-aerody...
My rather chunky Seat Leon 1.9TDi has 0.33cd.
Sooo....
How the hell can a car as 'slippy' looking as the Peugeot RCZ have such a high cd as 0.32/0.33??
Why do manufacturers use cd then, not cda, if that's more of a true representation?
See my car history on my blog at http://myasto.com/blog/
See my car history on my blog at http://myasto.com/blog/
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