Filling up question

[Tbird1983]

Not sure if this has been asked or discussed before so apologies if it has.

Obviously filling up to calculate tank to tank is easiest to track accurately but fuel has weight, eg a 45 liter tank filled is going to be a pretty significant weight increase. So in theory would only putting for example a quarter tank of fuel be more efficient? As this would be less weight to carry around?

My thinking is weight saving, i work from home and mainly do city driving so for stop and go less weight would be best correct?

[freebeard]

Like everything it depends. If the gas tank is behind the back bumper, it could alter the aerodynamic angle of attack.

As much as I've thought about it, it seems range anxiety would be higher.

I'd be more inclined to throw out the spare tire. They don't weigh less the farther you go and I haven't had a flat since I slid into a curb twenty years ago.

[mort]

Hi Tbird1983,
If you drive the same number of miles and get the same average MPG, then you've hauled the same weight of fuel, whether you carried it all from the start of stopped for gas every mile.
Carrying more weight does use more gas, but it's probably linear - I mean if 100 lbs lowers your car's MPG by 1 then 200 lbs would lower it by 2. Roughly speaking.
-mort

[Tbird1983]

Thanks for the replies, yea i guess its not going to make a huge difference in fuel consumption, but yea was just a thought LOL.

I am considering an ecu remap and dyno tune, its pricey but from what this company offers, i should see a 15-20% power gain and about 10-15% fuel efficiency gain.

[Autobahnschleicher]

The difference in fuel consumption would get eaten up by the increased amounts of trips to gas stations.
In my car I fill up all the way each time, ends up beeing maximum 41L or so aka about 30 kg of fuel or about 66 lbs for the metricly impaired.
That's at most 3% of my cars weight between full and empty.
If I filled up halfway instead of full, I'd end up making my car 1,5% lighter, wich is insignificant.
Ditching the spare tire and losing some weight would likely make more of a difference than 15 kg less fuel...

[redpoint5]

The difference in fuel economy is so small it wouldn't be measurable. Weight hardly matters, though it does matter more with stop and go driving.

A vehicle capable of regenerative braking will be impacted even less by adding weight.

[cRiPpLe_rOoStEr]

I'd rather do the tests starting with a full tank, as the "ballast weight" on short trips would still eventually provide a safer baseline to calculate range on longer stretches of road (or lack of road) with a less-than-optimal access to fuel stations.

[Tbird1983]

Awesome feedback, thanks everyone. Just dropped my car off at the mechanics, it has an issue with the cooling system, it keeps boiling the water in the reservoir bottle yet the heat gauge is only on half, ive had the car for just over a month and a full tank got me 550km only, mixed driving highway and suburbs about 50/50, its a 2012 chev aveo 1.6 LS, according to the specs it has a 45 l tank, so 12.2km/l, i have been doing mainly eco driving habits, timing traffic lights, coasting in neutral on downhills and to a stop at traffic lights if i cant time it right, driving slower etc and im still not even close to what the specs say i should be getting. Specs say approx 13.6km/l average.

Im hoping the water boiling issue is some of the cause of the higher than rated fuel consumption.

[Tbird1983]

i have this model, from South Africa, so km and litres here LOL

chevrolet aveo 1.6 ls 5-door 2012-4 - Car Specs - Chevrolet Aveo Specifications - Information on Chevrolet cars and Aveo specs for vehicles

[Tbird1983]

Mechanic just came back to me, car has a blown head gasket, just my luck, bought the car just over a month ago and its already giving problems.