Petrol is petrol. Or is it?
Apart from when things go horribly wrong, filling up your car with Tesco petrol or Shell V-Power petrol isn’t going to make much difference, you’re just spending an extra 10p per litre for a bit of branding, aren’t you?
The premium fuel conundrum has been bugging me for a number of years now, ever since I ran a Nissan 200SX and was certain I could tell a difference between a tank of Tesco’s regular and Shell’s Optimax. The problem was that I had nothing to prove I was right; was there really a difference, or was it just a placebo effect I created to justify spending the extra cash?
Last week I decided to finally find out what’s going on, so spent the day with Shell talking about their new V-Power Nitro+ Unleaded and Diesel fuels.
After a brief welcome from their V-Power Ambassador Jake Humphrey, I was fearful that this would be simply one expensive marketing day, but I’ll give Shell full credit for avoiding that for the most part as once Jake was through we were greeted by one of their fuels scientists and an engineer.
Concentrate, as Jenifer Aniston might have said in the 90s, here comes the science bit.
There’s a hell of a lot going on within a fuel, with upwards of 300 chemical compounds all reacting to each other under intense circumstances to create the bang that pushes your car forward. Unexpectedly, the diesel variant, seen by many to be a simpler fuel, contains more than 10,000 compounds.
The challenge for the white-coated scientists at Shell, and at every other fuel producing company, is to understand how each of these compounds works and to tailor them to extract the most performance from any given amount of fuel.
Performance doesn’t just mean power though, as there are more things to think about. We’ve all seen the TV adverts with pictures of gunked up valves and dirty engines. All that makes a huge difference to the efficiency of an engine, with even small deposits causing problems in getting the fuel and air into the cylinder quickly and cleanly.
Bear in mind that a valve is open for maybe open for around 40 milliseconds, and in that time a precise amount of fuel and air has to be thrust into the cylinder via a gap that is well under a quarter of a millimetre. You can probably now see why a build-up of carbon deposits is bad news.
Fortunately, Shell had a couple of engines that they had cut in half to show me exactly how critical these tolerances are, detailing exactly where the biggest issues occur and the problems they create.
V-Power, along with every other premium fuel, claims to be able to shift these deposits, something that can only be good news for your engine. Sceptical as ever, I asked just how long it would take to clear the heavy deposits shown on the example engines, but an answer wasn’t forthcoming. Plenty of prodding, nudging and cajoling later, a vague “between one and two thousand miles” was given as an answer, with a long list of terms and conditions attached.
Shell, start shouting about that. I guess your research might show that buyers expect it to be cleaned after a single tank, but I was expecting a year or so of normal motoring so to be told things could be improved in a month or two is a revelation.
Once your engine is cleaned up, is there any benefit? Shell showed me a test car they run, the first day it’s ever been seen by anybody outside of the company, to demonstrate the difference. It’s an ordinary Volkswagen Golf with a 1.4-litre petrol engine, but there’s a box of tricks bolted on to the top that allows an engineer to swap fuels while the engine is running.
Again, there were lots of explanations suggesting results vary depending on the time of day, temperatures, what you had for dinner last night and so on, but the numbers on the screen didn’t lie. The car produced around 4 bhp more when running V-Power than the alternative supermarket fuel.
They were then kind enough to throw me the keys for a Jaguar XJ-R, obviously fuelled up with V-Power, and point me towards an empty test circuit. Acceleration was unhealthily quick, cornering was very sideways and tyre smoke was notable even despite some slightly damp conditions, but sadly there wasn’t a sister XJ-R available with ordinary fuel on board.
So is there really a difference between the ‘normal’ petrol you and I buy every day and these expensive super-fuels? The evidence from the scientists suggests there is, but the lack of a back-to-back test on track still left me feeling a little cynical.
I’m going to give Shell the benefit of the doubt. For now. I’ll be running one of my cars exclusively on V-Power Nitro+ for a couple of thousand miles, geekily recording economy and details of what I feel from the car.
It may not be the most scientific test ever, but it’s the best I can do without investing millions in test rigs and equipment. I’ll report back what I find…
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