Hi, I am sure this will have been discussed somewhere just couldn’t find it. Having run my car (Mk3 2.0 Sport RC) on both a tank of regular unleaded (95 RON) and Super unleaded (98 RON) I am not sure there is any difference in performance. Is there any need to spend the extra £3 per tank on the higher octane fuel? I ask as I used to have a Boxster S and it did make a difference in that car.
Thanks
I don’t claim to be an expert but here is how I understand the situation…
The higher octane rating in fuel improves the engine’s detonation reducing the tendency towards ‘knocking’ or ‘pinking’ (which is bad). So running 98 octane would allow you to run a higher advance on your timing which in turn would give you more power. However, unless you actually have your timing remapped to take advantage of the new fuel then there is no advantage and your car continues to run with the default timing map.
So basically you wouldn’t see any difference in performance just putting 98 in your tank.
On your car with the MZR Ford engine yes it will make a difference, the engine being a more modern type has, I believe, a knock sensor and as such will re-map the ignition timing to make best use of the grade of fuel you are using, by putting a higher octane fuel in, it should advance the timing to suit.
This does not apply to the 1.6 engines and the earlier BP 1.8 as there is no provision for knock detection, unless a knock sensor has been retro-fitted along with a standalone ECU as part of a forced-induction set-up (turbo or supercharging)or if the car has been converted to run independent throttle bodies for example.
The BBR Turbo versions of the MK1 has a little switch in the centre console to select which grade of fuel you had in the tank.
The MZR engines do indeed have a knock sensor (if memory serves me right down the left hand side of the block) to alter the fuelling for a better quality fuel. Some say they have not seen a difference between the fuels though, I have found it does take a little while to alter fully at least two full tanks to really get an idea.
Currently using shell V Power Nitro stuff at the moment and getting around 38-39 and yes I do drive in majority at the moment roof down enjoying the revs somewhat.
On a recent motorway cruise of 80 miles - roof up way there - about 42 MPG, roof down on the way back 41 MPG - sitting around 70 ish.
Another way some have improved the MPG on the MZR’s is to disconnect the battery for a little while (note you will loose all MPG information and potentially the radio could be coded however they were NOT coded from the factory). This will then force it to relearn mapping and to a degree your driving style - doing this has improved mine from 35-37 to the more regular 38-39 I see now.
Am I happy with that yes I sure am nearly without fail the car is meeting or exceeding it’s MPG claims, something that I find utterly impressive in an era with all these up to MPG claims from manufacturers which very few people can get in the real world. Additionally, it is not like I am driving round like a granny to get that MPG either, maybe I should do a tank just driving slow hahaha!
In regards to other variables the car does seem “better” on the super unleaded fuel but this could be purely psychological.
Thanks for the replies. From my 2007 2.0 Sport I got 33 MPG on the last tank of Shell V Power Nitro on mixed roads. I have been pushing the car car a bit though as only had it a few weeks and still exploring the limits, so I was impressed with 33 MPG. As I mentioned in my first post it would only cost around £3 more to fill up on Super unleaded (Shell V Power, etc). I only fill up roughly once per month so a small price to pay for a little extra performance and I may get some of that cost back with slightly improved MPG as I understand it.
I think I’m sold, will stick with the higher octane fuels as I did with my Boxster S. If this was my daily commute car I would stick with regular as the cost would be significantly higher each month.
Actually based on my figures when running bog standard unleaded (getting around 35-36) to super unleaded (getting around 38-39) it actually works out cheaper to run super by about 50p per tank (based on achieving the same amount of miles) - last tank I ran to a 1/4 full - 320 miles - filling with super came to £4-5 more for me.
Mine is used everyday.
Taff. My car has a knock sensor. B6 engine! Fitted from new. Using 98 Octane on a long run I get 44 m.p.g. believe it or not! This fuel also contains better additives and detergents, keeps the fuel system clean.
Regards Geoff Peace.
TBH I think you kinda answerd your own question 