Petrol E10 and E5

[Jeff15]

Am I right in believing that E10 although cheaper to buy than E5 that E5 gives better fuel economy.?
I am wondering whether to go back to E5, your views please.?

[Jocko]

E5 tends to be 97 RON. E10 is 95 RON. I found that when I used 97 RON against 95 RON (both E5 at that time) I got marginally better mpg but not sufficient to justify the cost difference. The car felt smoother but that would make no difference to a Mk 4. In fact, because the engine in a Mk 4 mainly just charges the battery I doubt you would see any fuel saving. Try it and let us know what you find.

[Marco1979]

A year ago I started out on E10, but changed to E5 after a few fillings. The board computer gave a higher fuel usage and also the difference between bc and calculated when filling up was higher (on E10 bc was 0.4 l/100km off, on E5 only 0.2 l/100km off).
The engine runs more quietly on E5.

Also E10 tends to decompose a bit and attract water. Not good when the car is not used every week.

For me reasons enough not to use E10.

[Kremmen]

I'm going down the line that the manual says the engine is optimised for 95RON so E10 it is.

Here is a post I made years ago :

I've tried BP Ultimate Super Unleaded (97RON), Tesco High Octane 99RON), normal BP Ultimate (95RON) and normal Tesco unleaded (95RON).

To make the test more realistic, in my case (200 miles a week), I needed to use each for a month to ensure that on the last week I was still not running a cocktail of petrols.

and the results in my 1.8 i-shift = ........................

.............not a blind bit of difference with my mpg staying constant throughout, and no noticeable change in engine smoothness or performance !

The Which? magazine did a similar test with the same results across a range of vehicles.

[aphybrid]

If you can get a choice try
Not seen any choice in my area.

[Jocko]

Most supermarkets no longer sell E5. You have to use one of the branded stations.

[Karoq]

Tesco sell both in the Poole area.

[Jocko]

Tesco sells both here as well. That is why I said MOST supermarkets.

[SouthernExile]

I must confess that I always use Shell V-Power (99-RON) for my 120 or so miles a week, not because of any mpg considerations but because, like a well-known lager, it is reassuringly expensive. I can only hope that the car appreciates this lavish treatment. 

[Lord Voltermore]

I must confess that I always use Shell V-Power (99-RON) for my 120 or so miles a week, not because of any mpg considerations but because, like a well-known lager, it is reassuringly expensive. I can only hope that the car appreciates this lavish treatment.

Probably not.  They may run better on E5  or 97 Ron  but 99 Ron is probably  overkill.    But maybe 99 ron  ages better for low mileages. 
I use whatever is cheapest.  Usually E10 , but sometimes only E5 was available.   I accept E5 may be smoother running and possibly better mpg  but cant say I have noticed much difference.   

[Pine]

All cars suffer from a dip in MPG in the winter and hybrids appear to be affected more than normal ICE cars.  Since the introduction of E10 the dip in consumption seems to be even greater and I think there is a case for occasional, or even continuous, use of E5 unleaded.  This is just based on my own experience.

[peteo48]

E5 tends to be 97 RON. E10 is 95 RON. I found that when I used 97 RON against 95 RON (both E5 at that time) I got marginally better mpg but not sufficient to justify the cost difference. The car felt smoother but that would make no difference to a Mk 4. In fact, because the engine in a Mk 4 mainly just charges the battery I doubt you would see any fuel saving. Try it and let us know what you find.

That's been very much my thinking. The petrol engine is rarely under stress in a MK4.

[Jazzik]

I fill up with E95 E5 here in Poland and E95 E10 abroad and see hardly any (if any) difference in consumption.
And the engine running less or more smooth? No difference in my opinion...

[nowster]

The only time I've used E5 in a Jazz recently was to top up a car that hadn't been run in over two months, to displace potential dampness in the fuel.