My last two tanks of gas have me bumming out. I was averaging 50-51mpg and now it has fallen down down to 46 or at best upper 40s. Here are the suspected causes: Temps are upper upper 80 - lower 90s, so A/C is being used more Driving in some afternoon showers Too many Short, city drives Filled up at a station that has not given me good results in the past Not quite as vigilant in my hypermiling techniques My Fuelly. com trends are not good. I even bumped up air pressure to 39/37psi. In my tires. Any one else noticing it getting harder to maintain 50 mpg?
I feel your pain: You have already identified the primary problems: A/C, short trips, e.t.c. You might want to experiment with using 'efficient driving' on cruise control as an alternate protocol. There are no guarantees but it works for me. Bob Wilson
Car and Driver: Mileage? No, it's Your Gallonage that Really Counts | PriusChat Try running some numbers yourself to see what they're talking about.
You have the answers. Are you just wanting confirmation that it is normal? AC usage means lower FE. Rain increases the energy needed to move forwards. You know of all that water that sprays up from your tires as you drive down the road? Well the water was acted upon by your vehicles motive power, so for the same energy output less is used to go forward and more is used to part the water and throw it up in the air. Short drives means the cat isn't warmed up and you aren't in Stage4 driving until near the end of your trip. Filling up at various stations is usually more of a placebo effect that anything else. Generally it is the same gas from the same truck or at least same refinery. Having said that, I saw an extremely noticeable different between Shell gas and the cheap stuff at the convenience stores in my Honda Civic. It should not have made any difference and my scientific side says that it was pure coincidence. But for the extra few pennies, filling up at the Shell station with the Prius barely empties my wallet any more and gives me peace of mind with its placebo. As for hypermilling, if you are only getting low 50's with hypermilling there may be some technique problems to begin with. Addressing your tire pressures, you "bumped them up" to 39/37? In my book on the Prius those might as well be flat. Fill those suckers up to a few percent from sidewall max pressure.
My Prius is almost one year old and I'm getting 54.9 measured by Prius. I think you should wait 12 months and then look at your overall average. Using A/C will definitely lower your MPG since the ICE will have to burn more gas to recharge the battery.
Thanks, I am interested to know is there a way to test or measure if there is a technical problem? Bob can you elaborate on 'efficient driving' on cruise control as an alternate protocol. I'm all ears. Read more: http://priuschat.com/threads/5-mpg-drop-disappointing.129596/#ixzz2ZnxMxr6X Follow us: @PriusChat on Twitter | PriusChat on Facebook
I'm working on a set photos at home to show the technique. I took a couple of cell phone mpegs that show what the various states and how it works. In my case, I was using my 99.9 MPG loop to do laps. However, it works 'in real life' too and best of all, lets you concentrate on dealing with traffic. A happy accident, it also puts you in a mode to detect a 'dry tank'. <grins> Bob Wilson
