Im constantly getting 20MPG with my car and its starting to hurt my wallet. I don't really do big motorway trips, and most of the driving i do is about 3 miles before stopping again, but even so I'd expect more than 20MPG from a naturally aspirated car. The car in question is a toyota celica GT. Anyone have any ideas on what the problem could be?
Really bad MPG
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Soldato
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Could be a whole host of things. engine not timed properly, various sensors broken, o2, etc. Could also just be that as its only tiny trips the engine isnt getting warmed up properly and as a result fuel economy is crap.
Take it for a proper half hour run, get the oil nice and warm, let it clear itself up. Then try again perhaps?
Take it for a proper half hour run, get the oil nice and warm, let it clear itself up. Then try again perhaps?
Only 3 miles? What is the MPG meant to be on your car? 28mpg is quite low on long runs isnt it? unless you're progressing well all the way 
In 3 miles the engine really isn't going to warm up much and the car will be running richer for longer in these colder conditions. I get the same every winter in my 306 gti-6, I notice the mpg get noticeably worse on my 6mile journey to work.
In 3 miles the engine really isn't going to warm up much and the car will be running richer for longer in these colder conditions. I get the same every winter in my 306 gti-6, I notice the mpg get noticeably worse on my 6mile journey to work.
As has been said, 3 miles doesnt give the engine time to warm up properly, so 20mpg sounds about right for that sort of car. But if you're convinced it should be better, there are a few things you can look at
- Your driving style, to get decent mpg around town on short trips, you need to be driving very carefully
- Fuel is either being a)burned, b)unburned going through the engine, c)leaking. If it's a then it's doing what it should (engine wise anyway, see later suggestion), if it's b you can look at the spark plugs or put a cloth over the exhaust while someone revs it to see how black it is. If it's c then look for a puddle and a smell
- If it's being burned properly and it's still lower than it should be, then other factors are causing the engine to need more fuel. The most common one would be a binding brake - check to see how warm the wheels are after a run, if one is distinctly warmer than the others then its a sticking caliper causing extra resistance. Tyre pressures etc could have a similar effect
- Your driving style, to get decent mpg around town on short trips, you need to be driving very carefully
- Fuel is either being a)burned, b)unburned going through the engine, c)leaking. If it's a then it's doing what it should (engine wise anyway, see later suggestion), if it's b you can look at the spark plugs or put a cloth over the exhaust while someone revs it to see how black it is. If it's c then look for a puddle and a smell
- If it's being burned properly and it's still lower than it should be, then other factors are causing the engine to need more fuel. The most common one would be a binding brake - check to see how warm the wheels are after a run, if one is distinctly warmer than the others then its a sticking caliper causing extra resistance. Tyre pressures etc could have a similar effect
Agree, if you are doing no more than 3 mile trips, get a 125 or something, sounds stupid and pathetic, but seriously, get a moped, 10er in each weak, sorted
I fill up my bike ever 120 miles, it costs me £15-£18 quid dependant on how hard I ride it (mainly the latter of prices as I am only doing my commute atm meaning I'm ragging it as familiar roads). It is 11.5 miles each way, totalling in 23 miles a day, meaning that I fill up on average once every saturday.
And I ride a Ducati 748 (not the average bike... Built for the track)
ags
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I have a Jag x-type 2.5 V6 it unsurprisingly does around 20MPG. I can get 28mpg on average but it is bl*ody hard work.
Things that help:
Turn off the air con (massive improvement)
Don't fill the tank up to full, fill half to three quarters, then the car is not carrying so much weight around.
Barely touch the accelerator, especially down hill just dump the clutch in. (not that safe).
Try to change gears less and not bring the car to a full halt so much, gaining momentum continuously uses petrol.
Change the oil regularly so the engine does not have to work so hard also check you sparks or coil pack are clean, also check your filters your car needs to breathe.
And most importantly don't race chavs and boy racers off the lights.
Things that help:
Turn off the air con (massive improvement)
Don't fill the tank up to full, fill half to three quarters, then the car is not carrying so much weight around.
Barely touch the accelerator, especially down hill just dump the clutch in. (not that safe).
Try to change gears less and not bring the car to a full halt so much, gaining momentum continuously uses petrol.
Change the oil regularly so the engine does not have to work so hard also check you sparks or coil pack are clean, also check your filters your car needs to breathe.
And most importantly don't race chavs and boy racers off the lights.
Whats the point in having a nice Jag if you do that? Also I thought air con barely made any difference?
These are sensible
Awwwww, but thats the fun! lol
"yea blud, your superbike ent ****, my pug 206 with a sub the size of a house in the back will rip you up..."
<I wait at next lights as the tit missed the green whilst bragging>
ags
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Like I said generally I get 20MPG or under but I played around a bit to see what gets me the best mileage for the car.
Don't get me wrong I appreciate the growl of a V6 as much as the next man.
If you are only doing 3 mile short journeys, your car is never getting warm enough to get efficient, and will still be running an enriched mixture for the whole journey.
The other danger with such a lot of short journeys is your oil is getting well and truely abused, it will not be getting hot enough to burn off the condensation which in turn combines with nitrate by products from combustion to form acids. These can damage seals/gaskets etc if you don't change your oil a lot more often, circa 3000 miles, maybe even less.
The other danger with such a lot of short journeys is your oil is getting well and truely abused, it will not be getting hot enough to burn off the condensation which in turn combines with nitrate by products from combustion to form acids. These can damage seals/gaskets etc if you don't change your oil a lot more often, circa 3000 miles, maybe even less.
Soldato
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You know you're actually using more fuel by depressing the clutch and coasting right?
Its more economical to let the engine be turned by the road wheels.
"Elementary mistake - your car uses fuel in neutral (and coasting with the clutch), because the engine ticks over. Modern cars use no fuel at all if you just take your foot off the accelerator and coast. You can often see this in a car with a fuel mpg computer. So just stay in top gear, and coast."
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Doesn't it also have an adverse effect on the braking capability of the car, making it more expensive and less safe?
Soldato
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Well engine braking goes some way to assisting slowing down, and prevents you from speeding up rapidly. So basically you are more in control of the car. Its actually illegal to coast as well. If your coasting your going to have to use the brakes more. Other miniscule factors, clutch wear, release bearing wear, not to mention should you need to speed up for something etc etc.
Coasting is bad mmkay!
But the main point I was making is that when the car is engine braking, no fuel is being injected, as the road wheels are turning the engine itself.
If you depress the clutch the engine reverts to idle, and then the fuel is being used to keep it idling.
Coasting is bad mmkay!
But the main point I was making is that when the car is engine braking, no fuel is being injected, as the road wheels are turning the engine itself.
If you depress the clutch the engine reverts to idle, and then the fuel is being used to keep it idling.
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I had an agruement about coasting for the very same reasons just the other day 
I do think an oil change is needed, as its looking quite black now. And of course the light for oil pressure is on every so often which i've been convinced is just a dodgey sensor, but if not then the engine might well go pop some day down the line.
I do think an oil change is needed, as its looking quite black now. And of course the light for oil pressure is on every so often which i've been convinced is just a dodgey sensor, but if not then the engine might well go pop some day down the line.
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But also be aware that once the engine RPM reaches a set level the fuel will start being used again, for example in my car its 1500rpm, if you coast for a while say in 5th you may need to drop down to 3rd for example to keep the RPM above the set limit.
I was wondering about that - where does one find out what this limit is?