...how filling up the tank to full actually makes the car accelerate much quicker? I hadn't filled up the tank to full in over two weeks to keep the car light and quick....however yesterday I filled up the tank to full, and she seems to go like nuts!

I called my friend who has a Fabia too, and he agreed with me, and his theory is that maybe the ECU senses when the tank is near to empty and goes into 'economy' mode or something...

I don't know about you lot, but the needle certainly moves quicker when the tank is full, for one reason or another.

I thought VAG cars have an adaptive ECU, so whether thrashing it or not, shouldn't make the ECU go into a special 'Economy mode.'

I thought it was just me that had this theory. Maybe it's psychological rather than real. Perhaps the car is happy to be full again, whatever.... , but yep, I have noticed this phenomenon.

I don't suppose it's because there's no start/stop momentum in a full tank as there must be from fuel sloshing backwards and forwards in a half full tank?

Mo

dude its nothin like that. It's exactly how I described it...the car accelerates quite a bit faster when the tank is full, and i don't know why. I always thought the lighter, the faster, but the car IS slower on less fuel!

Not sure why this may be???? Thought initially that the fuel would have a greater head of pressure when full but as it then goes through a pump the pressure will be controlled and maintained by that??

Maybe its because of the greater weight of fuel at the back so your nose points up a little more giving you the top gun effect try running the tank low and putting a fat friend in the boot to see if it has the same results

This discussion has been had before, but regarding remapped 1.8Ts when some people suggested that the fuel pump wasn't "man" enough to keep up with the increased demand and needed the extra head.

try running the tank low and putting a fat friend in the boot to see if it has the same results

lol

no dude, it IIISS faster. If i calculate the 0-100 time on a stop watch it would defo be faster on a full tank than empty.

Perhaps we should all report back? Mine's nearly out; normally half fill it, but when I fill it full, I do get the psychological urge to put my foot down as I know I have enough petrol, so mine defintely accelerates better when full

Dunno how long it'll take me to monitor 0-100 over our local speed bumps though. I could be gone for some time

Mo

I hate not knowing anything, but if a petrol tank is half empty, the empty half must be filled with air musn't it? In which case, wouldn't that dilute the petrol so that a less rich mix would be taken for the engine? Dunno how it works, but can't believe there's a vacuum when the petrol empties out...

Regards

Mo

Sharpest knife

I called my friend

You've got one !

Old Cavalier diesel - three, four passengers and full boot - used to seem to pull better than when I was in alone.

Effect may be purely ps psyc psychiatric

It does depend a little bit on the diesel side of things, as the fuel heats up more quickly and that causes the ECU to back off a bit. Yes there is a return cooler but it doesn't do all that much.

Dunno if that same applies to petrols to some extent?

In any case, that only seems to apply when you get to 1/3rd tank or thereabouts, so you'd want to stay above that but not too much more, as the weight does have a rather more significant impact normally

So I'm not goin' nuts then, tis true!

Make sure its full in August when you take me for a spin Mil!!

'Wild Horses' wont make me miss a go in your car.

Cars can suffer with fuel starvation if driven hard below about 1\4 tank, so in a fashion Mil's right

most fuel tanks have a baffle in them to stop the fuel sloshing around when it's neary empty..

i think it may be something to do with the temperature of the fuel

Cars can suffer with fuel starvation if driven hard below about 1\4 tank, so in a fashion Mil's right

Which also explains why the tank seems to empty quicker when full than close to empty!

I sense the opposite. When the car is near empty it feels quicker than when full (just). Which makes sense to me as the car will be around 45 Kilos lighter at that point.

You've got one !

Old Cavalier diesel - three, four passengers and full boot - used to seem to pull better than when I was in alone.

Effect may be purely ps psyc psychiatric

Diesels love being under load. I used to drive trucks, and they felt lifeless with an empty trailer on. Load it to gross 44 tons, and it pulled like a.....like a.......well a truck really. Engine note changed, and you could feel the grunt.

Did you eat yorkie bars too?

I always thought it was because the car was no longer hungry.

I never feel like doing anything energetic on a full stomach.

I filled my tank yesterday and yup, it did feel alot more oooomphy - saying that I did put the premium BP in and the last lot was cheapo supermarket stuff

hmm, i'm not sure about this...

surely the fuelpump provides a steady supply of petrol/diesel at a given pressure, regardless of the volume of fuel in the tank?

ergo the engine gets the same volume of fuel at the same load settings regardless of tank level.

however, as stated, hauling up to 45kg LESS due to a nearly empty tank would make the car accelerate slightly quicker due to the lower mass requiring accelleration (IE the Power to Weight eould increase slightly!)

mil, how many Ferrari's have you taken like a king with a full tank?

compare that to the number you have done with a nearly empty tank and give us a definitive answer

If this theory is true, I think someone should tell the F1 boys before the season starts. Clearly they should be brimming their tanks before qualifying to help them get a faster lap.

If this theory is true, I think someone should tell the F1 boys before the season starts. Clearly they should be brimming their tanks before qualifying to help them get a faster lap.