Even before fuel prices started going mad I was trying to drive economically. My commute is about 30 miles of motorway and 10 of London dual-carriageways. That generally takes anything from 60 to 90 minutes with odd exception of much longer when the traffic gets totally messed up. So at best I am averaging 40mph. I drive a 2004 Vauxhall Zafira 1.9 Turbodiesel. The official fuel consumption figures are Urban: 37.2mpg, Extra Urban 55.4mpg, Combined 47.1mpg. The only way I have to check mine is by calculating from how many miles I get from a full tank to when I when I next fill it and I was getting around 47mpg. I try to keep a light right foot with minimal braking and gentle acceleration. I was doing 65-70mpg on the motorway and keeping to limits in town.
Recently I have been trying to improve on that. The main change is going down to 60-65mph. I still go over that if I need to overtake and not hold up the rest of the traffic too much. Going up hills I may slow a bit more. The result has been figures of 50 and 51mpg on the last two tanks. That is saving me nearly a penny per mile. The thing is that it probably doesn't make much difference to my journey time. For a fair bit of the motorway travel I can't even get up to 60mph. Those who do overtake me will just reach one of the several pinch points a bit sooner. So they may save a couple of minutes, but that's no big deal. I find driving a bit slower less stressful. I don't have to do too much overtaking. I try to go slightly quicker than the trucks so as not to slow them up, but also pass a few cars.
I would like to do even better, but that may require more radical methods. The so-called hypermilers go to extremes like coasting with the engine off and making major modifications to their cars. I would be prepared to invest some money on car parts if the payback time was reasonable. What I could really do with is a computer as featured on many cars that tells you the mpg at any given time so that I could adjust my speed, but I'm not sure I want to go much slower. I could try removing the roof bars that serve no real purpose, but I don't know if it would make a measurable difference. Any suggestions?
Another aspect of my driving is trying to help the general traffic flow. The first rule is good lane discipline. Often I see the overtaking lane full and the middle empty. Then someone will take a chance on speeding up there. I try to keep things moving at junctions. When it's busy then any dawdling can mean many people missing a change of the lights and spending more time burning fuel whilst getting nowhere. When the traffic starts speeding up after a slow patch I try to get away as quick as I safely can. Others leave huge gaps and so don't help the jam to clear. I'll often move into a slower lane where there is a big gap and let others get past me. I doubt that I make much difference, but if more people drove a bit less selfishly then it could.
The biggest difference I can make is by driving less. I am trying to do this by working from home more. In my line of work that is easy to do and saves me 2.5 hours of daily travelling. My employer is being fairly accommodating about this.
We hear a lot about carbon footprints and there are various sites that will calculate yours. The Carbon Account uses details of your mileage, meter readings and flight details to give a visual impression of how you are doing in certain aspects. I've just started using it. It's scary how big a contribution even a flight within Europe can make. I've done a lot of flights for work in the last few years, but not so much lately. We might do one a year for family holidays, but will look at other options such as the train. We recently took the train to Edinburgh and it was very convenient apart from a bit of waiting around. It was quicker than driving and no more expensive. Flying would have involved getting to and from the airports and probably not saved much time.