Shell Optimax

Introduction

Shell’s TV advertising is aimed at promoting their “Optimax” petrol to car drivers. It’s actually a cunning way to improve margins, since higher octane petrol costs the same to produce as does the cheaper stuff (but I am unsure of the tax implications). They have deliberately targeted the younger, or more enthusiastic amongst us, to at least try the stuff.

Personally, I’m not too bothered if Optimax gives the Ka a performance boost. I would not expect it to: the Endura-E is, after all, a reasonably simple engine kitted out with a sophisticated engine management system.

If the Ka’s electronic control unit can compensate for a higher octane rating in the petrol, it is possible that the car will use less fuel and show better performance. It would show more on a longer trip: a trip to Lincolnshire from York ought to show some difference.

In order to ascertain any reduction in fuel consumption from using Optimax, it will need to be used, continuously, for a period of time, then compared with ordinary unleaded fuel over a similar distance and driving. Running the odd tank full may well result in misleading data - the economy of the Ka varies quite a bit over different trips, depending on how and when the Ka is driven, the ambient temperature (and the weather in general), and the load in the Ka. Oddly enough, driving the Ka around on longer drives with just me in it doesn’t always produce the best economy figures!

Running on Optimax

When running on Optimax, the Ka felt quieter, smoother at very low speed, and had a more rapid pickup. He didn’t feel quicker in the conventional sense - he didn’t feel that there was more power or torque being released. Fuel consumption was also lower that we had seen before, but this remains unproven.

From my experience with diesels, these three benefits feel a lot like having the injectors cleaned. If this is the case, then initially, I would not expect to feel any significant difference between running on ordinary unleaded and Optimax, after a spell of running with just Optimax.

If, however, the Ka’s EEC-V control unit has adjusted itself for 98 RON petrol, then it should immediately feel different running on 95 RON.

Well, it’s louder. The engine is much louder running on the thinner, 95 RON unleaded compared to the more expensive 98 RON Optimax.

Shell’s Comments

On their web site, Shell claim that “Optimax is a completely new, highly refined unleaded petrol which burns more cleanly to give you smooth power delivery and increased engine protection. We went back to the drawing board to build the ultimate performance petrol and started by selecting the individual molecules which should go into the fuel. Using this approach and the same technology we use to develop petrol for the Ferrari F1 cars, we produced a unique formula: Shell Optimax - the best performance unleaded petrol in the UK.”

They go on to say that “Shell Optimax is completely new and created specifically for UK motorists who want to get the most from their car and from driving. It has the highest octane rating of any petrol in the UK which enables advanced modern design engines to work more efficiently and deliver more power. It is free of the heavy constituents which are found in other petrols and which leave dirty residue in the engine. It also removes these performance sapping deposits from the airways of the engine, so it cleans your engine as you drive. It protects your engine better than any other unleaded petrol.”

And on the note of fuel consumption, “customers in other countries where we’ve introduced similar fuels have reported fuel consumption benefits. And the West Midlands Police, who tested Optimax in their in their vehicles, noticed an improvement in fuel economy alongside the performance benefits of the fuel. So while we are not claiming fuel economy improvements in all cases, there is every reason to believe that many customers will see a benefit. This is because Optimax removes performance-sapping deposits from the engine as you drive.”

Initial Fuel Consumption Results

Running on Optimax: used 88·44 litres, covered 782·3 miles, and spent £68·48 over four fills.

Average Fuel Consumption: 40·2 mpg, interim high of 45·24 mpg and a low of 32·58 mpg.

Petrol Cost per mile: 8·75 pence per mile.

Next four fills (on 95 RON): used 108·32 litres, covered 897·6 miles, and spent £82·15 (adjusted figure: £81·13).

Average Fuel Consumption: 37·67 mpg, interim high of 41·57 mpg and a low of 30·06 mpg.

Petrol Cost per mile: 9·15 pence per mile (adjusted gives 9·04 pence per mile).

Driving Conditions: driven the same way, with a mixture of short city runs, the commute to and from work, and some long haul work.

Petrol Cost: the price of 95 RON petrol did vary during the testing period, with Optimax remaining at 78·9 pence per litre. 95 RON varied from 74·9 to 76·9 pence per litre. The Adjusted figure assumes that the 95 RON was always priced at 74·9 pence per litre.

Initial Conclusions

I always knew that it would be impossible for me to bring this section to a conclusion with irrefutable evidence that Optimax is “better” for the Ka than ordinary unleaded. And I am rather cynical of “wonder petrols.”

However, Optimax does appear to be more economical, but from my initial results, the difference in fuel economy does not make up the additional cost in buying the petrol.

However, the graphical and numerical interpretation of the above cannot detail how the Ka feels when running on Optimax - it’s quieter, smoother and has a better pick up. For this, I’ll need to do a little bit more research.

Watch this space for further updates!