25K Miles and counting

Having now got more than 25,000 LPG miles under the tyres of the Outlander it's time to look at the numbers again.

So, since the 21st May 2009 i've been recording all the LPG fuel used, the cost and the mileage. The result shows two consistent periods of average MPG running with some explained spikes. Firstly, the original install was not fuelling properly for two reasons. 1) there was an installation error meaning that one of the fuel pipes from injector to manifold was pinched and couldn't flow at full rate and 2) fuel trimming was too high and needed a software change. It took a long time for these tow issues to be resolved because my initial trip to thinkgreencars didn't find anything and then it took a couple of trips to Northern Autogas who are more local to me before they found the problem. Having had these two issues fixed the car drove a lot better with no noticeable power difference from petrol. However, this was at the detriment of the now free flowing fuel so the average MPG post fix was and is 1.5 mpg worse.
This graph shows the mpg, overall average and moving 10 fill average for the last 25k miles.

Click for a larger view. Two other points to note are the significant low spike in early December 09. This was our trip to Scotland and we spent a lot of time on minor roads compared the normal 90% motorway commute. Also, during Jan and Feb 10 there were a couple of low spikes. These coincide with the worst of the snow and the extra gas required to drive in very tricky conditions and with lights and aircon on all the time.

What this did to the cost of running the vehicle can be seen in the following chart. Here you can see that the cost of running per mile has increased steadily from 11ppm to 14ppm. This is a combined result from the change in economy and increasing fuel costs. again, click for larger view.

Other figures of note: Average cost of fuel 53.7 pence per litre with a high of 64.9 ppl. We also run a diesel car and comparing the cost of running that the Outlander started of with an equivalent mpg of around 46mpg and has now fallen to 37mpg.

All in all, thus far, the running costs have been as expected with a lower variability than running a petrol or diesel car due to the greater consistency of fuel prices. As we approach the 12 month anniversary it's time to start thinking of a replacement vehicle and again an LPG powered car is on the cards. More details next time.