Supermarket Fuel vs BP Diesel

I usually fill my Honda Accord i-CDTi with regular, supermarket diesel for the reasons most other people do: convenience (that’s where I shop) and price (it’s cheaper than the named brands).

I tried an experiment a couple of weeks ago though – I was at a BP filling station and I thought I would put some BP Ultimate Diesel in to see if it made any difference. No real difference was noticed in general performance, although fuel economy appeared to improve by slightly more than 5%. The problem is that doing experiments with fuel is quite a long process – I always wait until the fuel light comes on (about 10 litres remaining of a 66 litre tank), and then fill it right up. Amount in = amount burnt, which makes it easy to do fuel economy calculations. For me that’s in the region of 450 miles, which at present (luckily for me) is three or four weeks’ worth of usage. Across those lengths of time, other things which affect fuel consumption change too, such as the weather – humidity and air temperature being the two main variables.

I went back to the supermarket diesel for a back-to-back comparison and hated it immediately. Within half a mile of leaving the forecourt, I noticed the car was lumpy to drive and hesitated low down in the rev range (especially before the turbo had spun-up). Drifting along with a slight amount of throttle in either 2nd or 3rd became a pain and overtaking when not on the motorway really made you wait for the engine to confirm it was going to deliver the torque and then go for it. This seemed to ease off a little the further through the tank I got, but it was still poor.

I’ve heard bits and pieces in the past that modern engines adapt their behaviour to suit the quality of fuel provided, so maybe it was making the best of what it could. Don’t know if that’s true or not. But either way, the supermarket diesel was much worse than the BP stuff. So the moral of the story is that BP Ultimate Diesel for me is worth it.

Or so I thought.

Having thankfully got to the bottom of the last batch of supermarket fuel, I went out and filled up with some more BP Ultimate Diesel. For a variety of reasons due to circumstances beyond my control, I didn’t see the price of the fuel before I started to dispense it. This stuff is priced at an eye-watering 109.9p per litre – the most I’ve ever paid for fuel. For those not in this country, 109.9p per litre at today’s exchange rate (at CDN $2.03 or US $2.06 per UKP) is a whopping CDN $ 8.45 / US $ 8.56 per US gallon.

Now I paid nowhere near 109.9 for the diesel the last time I put BP fuel in, so I’m thinking maybe I only put regular BP diesel in last time. I’ve got 50 litres of the stuff, which better be good! I think next time I’ll probably stick with the regular BP diesel and avoid the supermarket stuff.