So which petrol is really cheaper then

Mishomeister

Having found out that due to the recent changes to petrol I will now have to fill up my car with more expensive 'super octane' petrol I was jealous to many drivers that will not.  
But here is the observation that I made today:
Super unleaded cost 1.41 at Tescos. And the normal petrol costs 1.34 so 7p difference si roughly 5% difference.
But the new petrol is 10% less efficient meaning you will be able to drive 10% less distance with it?
Making it technically 5% more expensive that super unleaded?

TadleyBaggie

Mishomeister said:

But the new petrol is 10% less efficient

Do you have a (reliable) source for that assertion?

facade

Ethanol has around 70% the energy content of petrol for the same volume.

I think, but I don't know for sure that e10 is 10% ethanol by volume, so that would mean around 97% of the energy content of super (0% ethanol).

So assuming total efficiency, if super is less than 100/97 x the price of e10 (3% more) then it works out cheaper.

There isn't much in it.

https://afdc.energy.gov/fuels/ethanol_fuel_basics.html

https://www.eia.gov/tools/faqs/faq.php

[Deleted User]

I've always used the 'good' stuff even though it costs more. I reckon it's worth the extra few quid a week as it could keep the car in better condition long term. I don't know if it will but I'm willing to pay the extra. (Touch wood) but I've not had any major mechanical failures since doing this over the last 7 years.

Thesaltmustflow

Deleted_User said:

I've always used the 'good' stuff even though it costs more. I reckon it's worth the extra few quid a week as it could keep the car in better condition long term. I don't know if it will but I'm willing to pay the extra. (Touch wood) but I've not had any major mechanical failures since doing this over the last 7 years.

Having watched a few videos of 'experts' testing all the different fuels available in the UK, I found it surprising that the tests concluded there is actually very little difference in performance, longevity and engine wear of E5 and E10.

I use the 'good' stuff in my bike not because it's a sports bike and it 'needs' it but because I choose to but in the petrol car I used to have I always went for the cheapest available. I'm now driving a BlueHDI so all Diesel is (from what I can gather) much of a muchness UNLESS anyone can tell me otherwise? 

uknick

I can't comment on the E5 & E10 issue, but if you've a car designed to run on 98 octane or higher, i.e. super unleaded it'll probably give you better efficiency.  If not, yes it will be more expensive.  However, if your car needs super to ensure various components don't prematurely wear out, surely it will be cheaper in the long run.  Having said that I do have sympathy with drivers who have to change. 

With regard to the efficiency, I owned a Cayman for nearly 9 years and about 80k miles and mainly ran it on super unleaded, Tesco Momentum 99.   On occasions I did a test with normal unleaded and found Super gave me about 5% better mpg.  During the comparison I tried to get a like for like environment, e.g. same time of year for about 3 months.  I'll admit it was no more scientific than that.  But, whether the 5% is more cost effective all depends on the price.  Generally, Tesco 99 was only about a couple of p per litre dearer.  Any more than that and it would not be more cost effective.

However, there is absolutely no doubt in my mind, the Cayman ran better on super, no surprise as that's what it was designed to use.  It was more responsive at low revs and seemed to have better pull during at the mid range.

coffeehound

Since some/most/all Super fuels also include fuel system cleaners, you could subtract the cost of an occasional Redex treatment from the fuel bill, too.

Thesaltmustflow

coffeehound said:

Since some/most/all Super fuels also include fuel system cleaners, you could subtract the cost of an occasional Redex treatment from the fuel bill, too.

Would that also apply to Diesel? 

The reason I ask is having recently gone back to Diesel (albiet BlueHDI and supposedly a clean Diesel) I do not know if the vehicle I have bought has ever had any fuel system cleaner. I recently filled up with Shell V-power Diesel and will probably just use the V-power every few months BUT from what I've read ALL Diesel contains a cleaning/lubricating agent so am I wasting my time 'treating' my new car to V-power (or a similar super Diesel) and should I just use the standard B7?  

coffeehound

Thesaltmustflow said:

Would that also apply to Diesel? 

The reason I ask is having recently gone back to Diesel (albiet BlueHDI and supposedly a clean Diesel) I do not know if the vehicle I have bought has ever had any fuel system cleaner. I recently filled up with Shell V-power Diesel and will probably just use the V-power every few months BUT from what I've read ALL Diesel contains a cleaning/lubricating agent so am I wasting my time 'treating' my new car to V-power (or a similar super Diesel) and should I just use the standard B7?  

I don't know anything about diesel, @Thesaltmustflow.  I saw evidence that the petrol had greater cleaning power than ordinary 95 unleaded.  Even then people will debate whether it's actually necessary to clean fuel systems and cyclinder more than with ordinary fuel and so it's difficult to draw firm conclusions.  Hopefully people with diesel knowledge can advise you on that question.

Dr_Crypto

Are there even different grades of diesel? I’ve only ever seen the standard black nozzles and I too drive one! 

Car_54

coffeehound said:

Since some/most/all Super fuels also include fuel system cleaners, you could subtract the cost of an occasional Redex treatment from the fuel bill, too.

I've been driving for 50-odd years, clocking up massive mileages, and have never once used Redex or any similar snake-oil product, nor bought any "super" petrol, even when the company was paying. Have I been going wrong?