Fuel problem?

[ne4sta]

hi,
today me and my gf drove from london to brighton (about 46 miles there 46 back) and the car used half a tank of petrol.
on the way i could smell petrol (or fume like smell) when we arrived popped the bonnet we saw that from 2-3 days ago of her filling up the oil tank she had left the cap on the engine n lost it, so we drove for 46 miles with no oil cap on. this was obviously the smell as in brighton we bought a replacement cap and the smell stopped but the car still did a 1/4 of a tank back.
is this normal? we cant seem to work out if half a tank for 100 ish miles is normal or not. theres oil and water in the car and the temp seems fine.
the car is

2002 vauxhall corsa 1.2 SXI 16v

 

[Spark123]

How many gallons of fuel is there in 1/4 of a tank?
How much oil did you lose? I take it you topped it up?
Is the engine misfiring?
When's the last time it was serviced?

 

[Mursal]

Well if she was my GF, she would be an XGF.

To treat a fellas Corsa like that, she must wont to call it all off, does she?

Looks as though you got away with it. If it used less petrol on the way back, then your car musen't have summered any long term damage.

After what you two have just gotten away with (not completely destroying a good engine) I wouldn't even bother worrying about fuel consumption until at least Christmas.

But if she steps out of line (again), don't hesitate to mention the missing oil cap to her!

 

[ne4sta]

Lol well I'm looking into trading her in now!

On the fuel issue though, I read that the car holds 9.9 gallons alprently bit I'm not sure it's really that high, costs about 40-45 quid to fill it up at about £1.18 litre.
But were pretty sure it doesn't usually use that much fuel for that sorta journey my maths (which is really bad ) worked out we were doing about 23mpg but someone may wanna check my maths.
Also no leak at all under the car or anywhere

 

[Mursal]

Sounds a bit hard all right. Might need an air filter change?

Or you have a petrol leak under the bonnet (or somewhere else) as well. It must be quite messy after all the oil?

 

[TicklyT]

Bear in mind the average fuel gauge isn't the epitome of accuracy. IME a reading of half full can mean anything between 1/4 to 3/4 full.

With some cars it look like the needle is painted onto the gauge scale, but when it does start moving, you end up racing it to the next garage.

And the gauges on some cars read empty when there's still a couple of gallons left in the tank.

If you really want to check your fuel consumption accurately, note your mileage, brim the tank, make your journey, then note the mileage and brim the tank again, preferrably using the same pump at the same filling station, noting how much fuel it takes to top it up.

Divide the fuel used in litres by 4.54 for gallons, then divide the miles covered by fuel used in gallons for miles per gallon.

The fuel consumption figures quoted by manufacturers are often far from what you can ever hope to achieve in the real world, because the test conditions are artificial - who drives at a constant 56 MPH along level roads in top gear all day, every day? In modern traffic conditions on some roads, even reaching 3rd gear could be considered adventurous!

The manufacturers figures are useful for comparing the general characteristics of different vehicles, as they all have been subjected to exactly the same artificial tests.

 

[Mickymoody]

The oil cap is there, to maintain pressure within the engine, so without it, it vents the gasses within the engine, that are recirculated within the engine. So in theory, these gasses help the engine to produce more power, but in reality, clean air is best to combustion, and reintroducing extra gasses might help, but don't help.?

 

[iwaters]

Well if she was my GF, she would be an XGF.

To treat a fellas Corsa like that, she must wont to call it all off, does she?

Looks as though you got away with it. If it used less petrol on the way back, then your car musen't have summered any long term damage.

After what you two have just gotten away with (not completely destroying a good engine) I wouldn't even bother worrying about fuel consumption until at least Christmas.

But if she steps out of line (again), don't hesitate to mention the missing oil cap to her!

Least she checked the oil and topped it up. I said to the wife the other week, 'when was the last time you checked the oil in your car'. The reply was 'I don't know how to do that, its your job anyway.'