You would think that the 1300cc engine would have the best fuel economy but on the open road it seems that engine could be working harder at 100k and therefore chewing through the same amount of gas as the 1600cc or 2000cc engines which don't have to work as hard, depending on gear ratio's,. Maybe!
a.woodrow,
Jun 3, 10:01am
cc ratings so close together are fairly irrelevant, more would depend on the type of engine and what vehicle it is in
andrea_w,
Jun 3, 10:02am
Engine capacity doesn't reflect economy. there is a lot more to it than that
bikernutrr,
Jun 3, 10:05am
I see small engine cars advertised claiming 'cheap on gas'. Maybe on short trips but on the open road I don't think some of them are that 'cheap' to run
a.woodrow,
Jun 3, 10:08am
Big engined cars come into their own on the open road, I had a v6 vt calais which I could get down to 7L per 100km. many smaller engined cars would only be marginally better
bikernutrr,
Jun 3, 10:09am
That sounds pretty bloody good!
morrisman1,
Jun 3, 10:23am
A larger engine, all things including manifold pressure being the same, would have a lower RPM to produce the same kilowatt output, going through the appropriate gear ratios to achieve the same torque at the wheels and hence driving force.
Lower RPM will mean significantly lower frictional losses in moving parts like alternators, bearings, reciprocating motion, piston-cylinder friction, water pump etc. With the lower frictional losses you would expect better gas milage.
An engine is most efficient when the throttle is wide open, that way volumetric efficiency is maximized. Because the friction will be linear with RPM rather than throttle position, having the throttle wide open (hence higher manifold pressure) and the RPM lower will end up more efficient. What Im trying to say here, is if you can achieve 50hp with the throttle open at 1500 rpm, or 50hp with the throttle at half at 3000 rpm, the wide open engine will be more economical than the half throttle one because it has lower frictional losses. Slightly off topic I know but still relevant.
In practice however cars will normally run much richer when the throttle is open in order to prevent detonation and also the ignition timing comes back for the same reason and this makes the engine less economical than perhaps its potential is. So Im not recommending using the highest possible gear and using full throttle because that will probably chew gas because of the car's computer tuning.
morrisman1,
Jun 3, 10:27am
Also to add, most of the open road economy will come down to the drag of the car rather than the engine's size. If you don't use the brakes then weight of the car will become less of a factor (a heavy car will coast further than a light one, and while you are coasting its basically free miles).
robotnik,
Jun 3, 10:31am
Some large engines from the likes of Chrysler and Holden come with a cylinder shutdown technology. So for a small weight penalty you get the economy of a small engine out of a V8 or V6. These days displacement means nothing when it comes to fuel economy.
msigg,
Jun 3, 10:32am
Yes a smaller engined car is cheaper to run, sometimes not by very much, but arount town/hills lights/etc yes they come into there own more.
thejazzpianoma,
Jun 3, 10:33am
As said above CC rating is pretty much irrelevant. The equation is far from a simple one nowadays as engine technology is so varied.
We now live in a world where a Commodore sized Passat Wagon is available with a 1.2 litre engine that pulls it along very well and with excellent efficiency.
Technology's like Direct injection, independently variable valve adjustment (Fiats Multi-Air), multiple stage turbos and super charging make drawing any useful comparisons on CC rating impossible.
AND. thats before you get on to the technology in the rest of the car. Electric power steering, automated manual transmissions, and a whole host of other technology's make a huge difference to a vehicles efficiency long before an engine is even bolted in to place.
So. if you are looking for an economical car look at its use of technology before you look at CC rating because cars like the 2.0 FSI VW Golf use less fuel in the real world than pretty much any of the 1300cc 4 speed automatic low tech Japanese cars of the same age that people buy in the hope of making fuel savings.
bikernutrr,
Jun 3, 10:39am
x1
A lot to consider when purchasing another car.
thejazzpianoma,
Jun 3, 10:48am
Yes and no. There are two things that will give you some good clues as to a cars efficiency without getting too technical. Those two figures are: 0-100 times Fuel economy figures. (Just make sure you are not looking at Japanese figures as those are set up to make Japanese cars look more efficient than they are, you want real world or European standard ones)
Then, just look for a car that has a reliable direct injection or common rail diesel engine and either a manual transmission or a dual clutch automated transmission (Like VW/Audi/Skoda's DSG or Fords system). If you are looking at older cheaper cars then CVT may be an option but again you want a reliable version with an external oil filter and one that has been serviced properly.
Really though, if you just post your budget and intended use we can put some options out there to consider.
Most importantly do your own math, most people don't bother and work on silly generalisations and what the media tells them is good, they usually end up buying cars that are far from efficent as a result.
If you need proof of that just look at how many sheep buy new Hyundai diesels thinking they are getting something economical and good vale for money because thats what the marketing tells them.
bikernutrr,
Jun 3, 10:58am
Just looking. but undecided on purchasing extra car or not. Only wanting car for literally A to B at mostly open road speeds. Budget would be as cheap as possible :) don't care about age, milage, just about cheap fill ups.
bikernutrr,
Jun 3, 10:59am
Sound like I'm trying to push S#@T up hill! haha.
thejazzpianoma,
Jun 3, 11:09am
The open road speeds are a big help as older technology's are at their very worst in city conditions.
I am still a big fan of the Fiat Punto's from 2000 onwards, they will give you some very up to date technology and phenomenal economy yet are affordable to buy. You can pick them up from about $3500. Both CVT and Manual ones are economical. You would be looking around 5l/100km for mostly open road use depending on which version of the 1.2 litre engine you have and whether its manual or CVT. Becase the vehicle is so efficient the 1.2 twin cam CVT will out perform a 1.6 Automatic Corolla of the 1990's while using significantly less fuel. Yet both cars cost a similar amount to buy.
Cheaper than that and you can still get economical but you start to sacrifice safety and comfort.
I can give you some cheaper options though if you wish.
bikernutrr,
Jun 3, 11:14am
Thanks. I also have seen some cheap diesel cars(with high kms of course) but look ok for just A to B. But I suppose there is road user as well.:)
thejazzpianoma,
Jun 3, 11:17am
The cheap diesels will generally be older technology as well which means not that economical and very frequent and expensive servicing.
I made a website www.dieselvspetrol.webs.com which will help you calculate the difference. I have not updated the fuel prices for a while but you can update these yourself by over writing them if you wish.
In short though, if you are not towing, or needing a large car in the cheap as possible price range petrol is the way to go. Different story for newer vehicles and different types of running etc.
thejazzpianoma,
Jun 3, 11:20am
BTW, 20'000km service interval on the Punto and a cheap service when it rolls around too. The CVT however will need servicing every 40'000km at say $400 a time so buy a manual one if you want to avoid that.
thejazzpianoma,
Jun 3, 11:23am
You are most welcome. BTW, if you decide you must have a diesel, the cheapest new technology diesels (common rail) are generally Citroen/Peugeot's and occasionally you will get a cheap Fiat Multipla. Avoid automatic Citroen/Peugeots and most have badly designed auto's that can't be serviced properly/easily and fail at great expense any time after about 130'000km
But really, Fiat Punto petrol is the car to beat for economy and also as a decent safe, reliable and well featured vehicle for very little money.
bikernutrr,
Jun 3, 11:26am
Actually I think I might steer clear of a diesel as I do prefer petrol anyway. Sounds like technology is the way to go.
thejazzpianoma,
Jun 3, 11:29am
Generally yes. you could buy a real bare bones old technology car and get similar economy (Like a Daihatsu Charade) but the reason they get the economy is because they weigh nothing. the catch is they weigh nothing because they have absolutely zero safety and comfort features.
So yeah, you are getting the idea, clever design like you get with the Punto will provide you the best of both worlds.
Best of luck!
thejazzpianoma,
Jun 3, 11:29am
Generally yes. you could buy a real bare bones old technology car and get similar economy (Like a Daihatsu Charade) but the reason they get the economy is because they weigh nothing. the catch is they weigh nothing because they have absolutely zero safety and comfort features.
So yeah, you are getting the idea, clever design like you get with the Punto will provide you the best of both worlds.
Start looking for any other 4 Star NCAP cars in your price range with similar economy and you will quickly see what I mean. (Pretty much nothing else comes close in that price range)
Best of luck!
r.g.nixon,
Jun 3, 11:39am
Like my Subaru Ace (800cc, economical, unsafe and very noisy!)
foxdonut,
Jun 3, 12:42pm
The only thing that dictates fuel economy is the driver. Everything else is down to harmony and efficiency.
Manufacturer claims of "x litres per 100 / mile per gallon" etc are pure speculation unless they're tested by third parties that have a standard of criteria they stick to.
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