My car's current overall stats. are: 41.4mpg (on E10).PhilHornby wrote: ↑Wed Aug 16, 2023 11:52 pm A month ago, I did a 600 mile day-trip in six stages (i.e. coffee breaks etc). This was at motorway speeds and I noted that the economy for each leg of the journey started with a "3" - let's say the average was 38mpg... (I'm due to repeat this trip in September, so I may experiment then).
The odometer says 6830.3 miles in 14:08h (so something's overflowed, or been lost!).
My average speed is very low, since most journeys are around North Devon and I live 15 miles from a dual-carriageway!
I have some figures from the latest trip.
(It is of course, quite difficult to completely empty the tank of one fuel type and replace it with another. I filled up with Total E5 near Bridgwater (low fuel light was on) and drove 47 miles home. (This segment only recorded 34mpg). The following morning I topped up again with Murco E5 (only the best for me
), before starting my trip to Yorkshire and back).I did the whole outbound trip and 150 miles of the return trip before needing to refuel. The overall consumption was 41.6mpg (393.9 miles at an average speed of 59.7 mph). SCC was engaged most of the time (including during the rolling-road block I got embroiled in!). Some 30 miles were on 'ordinary' roads, to avoid chaos on the A1. "ECO" engaged except when in outside lane, where I use "SPORT" mode (because it greatly improves throttle response).
For comparison, the remaining 152 miles home on (largely) E10 were achieved at 34.4mpg at an average speed of 65mph.
There was, of course, variability in traffic and weather conditions. I paid about £1.61 per litre for the E5 (where E10 would have been £1.51/litre).
[A full tank of BP E5 at Michaelwood services, would have set me back an outrageous £108! (55x£1.959)]
It's still quite difficult to make direct comparisons, but the fact that the car averaged almost 400 motorway miles at the same mpg as it normally achieves trundling around, is a definite improvement (in my book). I don't think it would be fair to compare 41.6mpg against that final 34.4mpg E10 leg - not least because the terrain gets hillier south of Bristol, but I would use my estimate of 38mpg from the previous trip.
Let's say mpg improved by 41.6/38 = 1.095. E5 costs roughly 1.066 times as much as E10 (1.61/1.51) . It would increase the range on a full tank to 55/4.544x41.6 = 503 miles, from 55/4.544x38 = 460 miles.
For my trip E5 would have saved me about £2.18
I didn't notice any difference in performance or driveability.
