Petrol

[onevia13]

Not necessarily...quality of the fuel depends on the content of hydrocarbons inside the solution and impurities...

Let me educate you a little since im studying organic chemistry =P

Octane content is important because it gives off a good amount of energy when you burn it and it forms CO2 and H2O being more stable than a long hydrocarbon chain. According to wikipedia it gives off standard enthalpy of −5430 kJ/mol in combustion. (Enthalpy = the change in energy when a reaction occurs. "-" means exothermic reaction and energy is given off, positive integers means endothermic and energy is absorbed)

Fuels that dont have as much of these nice long chains (Octane +) and have more Ethanol (E10) and thus do not give as high energy when burnt. Wikipedia suggests that Ethanol's standard enthalpy for combustion –1370.7 kJ/mol.

So from these figures you can see that 1 mol of octane gives off more energy when combusted (which is expected because octane has more carbons and more hydrogens, as well as one mol of octane is heavier than ethanol). However as it turns out i just worked out the Molar Mass of ethanol which is 46 and octane is 114.. so actually in octane you are getting 2x the amount of energy per mol combusted even when you get near equal mass amounts

Also quality of fuel takes into account less impurities such as sulfates that are usually found inside crude oil so when you talk about "Good quality fuel" such as VPower and Ultimate, they have less impurities because they have been processed that much more (more filtration, purer fractional distillation)

Therefore the "purer" the fuel, the more energy you actually obtain from the combustion because theres more hydrocarbons per drop....less impurities such as sulfates that dont give off a lot of energy when combusted. Pure ethanol also vaporises quite quickly so you may actually "lose" a little in the combustion process. (which is the fuel smell when you open your filler cap...some fuel has vaporised)

Thus in comparison your engine works like this:
I need X amount of energy to accelerate from 0 - 80km/h and with fuel with no ethanol it takes "O" amount
the same X energy for acceleration from 0 - 80km/h requires "E" amount from E10 which is a x% more than the amount "O"

So every time your car needs to get up the same hill, will need to use that much x% more E10 than O

I hope this deserves a PQ point =)

I see what your saying in regards to the comment, about the BP ultimate eating more fuel- i agree that its not entirely true, yes it may cost more than the lower grade fuels, but thats just because like you said, the purity of the 98 octane, my understanding of organic chem is that yes a more pure form of a substance/ molecule means less impurities, so that the engine should be burning the fuel more efficiently and also providing more power in each reaction/ products produced, instead of different compounds (higher concentrations of them/more) making up the ultimate mix, meaning that because it's not as pure the reaction rate for each product in the fuelis different, which i assume leads more residue forming/ left (as seen as black smoke/ carbon by most)and not efficient energy production as the engine is trying to get through more compounds than it is built to by the manufacturers (so lower grade fuels may just mean burns off faster if its a low molecular wt), so yeah higher grade petrol=higher concentrations = costs more (what did you expect for more of something), the price you have to pay for better performing cars.

[ekay1]

I see what your saying in regards to the comment, about the BP ultimate eating more fuel- i agree that its not entirely true, yes it may cost more than the lower grade fuels, but thats just because like you said, the purity of the 98 octane, my understanding of organic chem is that yes a more pure form of a substance/ molecule means less impurities, so that the engine should be burning the fuel more efficiently and also providing more power in each reaction/ products produced, instead of different compounds (higher concentrations of them/more) making up the ultimate mix, meaning that because it's not as pure the reaction rate for each product in the fuelis different, which i assume leads more residue forming/ left (as seen as black smoke/ carbon by most)and not efficient energy production as the engine is trying to get through more compounds than it is built to by the manufacturers (so lower grade fuels may just mean burns off faster if its a low molecular wt), so yeah higher grade petrol=higher concentrations = costs more (what did you expect for more of something), the price you have to pay for better performing cars.

Good point there. I also believe that the better grade petrol you use for your car, the longer the engine will go and will generate less problems in the long run rather than using cheap petrol. Sort of like giving a human cheap food vs good quality food, the good quality is gonna satisfy and going to be better in the running. I just think of the car as a human :P