Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - We need an "MPG aware acceleration computer"

stillsearching · 09-06-2012, 07:29 PM

Was reading another thread asking how different rates of acceleration affect mileage, when the total amount of energy to get to X speed should according to physics be constant whether applied over 30 seconds or 3 seconds... see thread for the discussion.

Reading through it all made me aware that maybe hypermilers need even better gauges to get more insight.

I mean we have realtime MPG readouts but that only shows best cruise speed for instance, it does not necessarily show the most efficient way to accelerate necessarily (keeping the figure low may unnecessarily piss off traffic behind you plus the BSFC is less efficient at loads below a certain level) and even if you learn a good habit for say driving on familiar mostly flat roads, if you travel and end up in hills the same strategies may not apply the same trying to accelerate uphill for instance.

I would think a realtime BSFC map would be ideal, especially one taking partial throttle loads into account. (I have to assume at half throttle the figure changes slightly at a given rpm and load, just like other aspects like torque change) For that matter a realtime torque curve display, depending on throttle. Or other graphics that might be useful for helping the "human computer" decide how much throttle to use and when to shift, something a little more complicated than the "shift now" light on most cars. In heavy traffic where I can't drag my rear it could still provide assistance to suggest how to accelerate more efficiently under those conditions. Or maybe i'm towing a small 1000lb trailer and that totally changes the physics of the car I was used to driving in a certain way before. Or I have a couple kayaks on the roof rack throwing off the aero but affecting weight minimally.

There's so many variables that it's really more in the realm of the computer. And since carputers and cheap LCD's are available now it shouldn't be that hard actually to make something. The main questions are to figure out before anything what data is actually the most useful, beyond the realtime MPG display. The realtime MPG display is great for highway cruising under all loads because it accurately represents what you will be using. It does not give terribly useful information for "pulse and glide" calculations, varying highway driving conditions (unable to pass or set a steady state), nor in town. So what could we do to improve it?

09-06-2012, 07:29 PM	#1 (permalink)
stillsearching EcoModding Apprentice Join Date: Dec 2011 Location: Minnesota Posts: 201 Thanks: 45 Thanked 8 Times in 7 Posts	We need an "MPG aware acceleration computer" Was reading another thread asking how different rates of acceleration affect mileage, when the total amount of energy to get to X speed should according to physics be constant whether applied over 30 seconds or 3 seconds... see thread for the discussion. Reading through it all made me aware that maybe hypermilers need even better gauges to get more insight. I mean we have realtime MPG readouts but that only shows best cruise speed for instance, it does not necessarily show the most efficient way to accelerate necessarily (keeping the figure low may unnecessarily piss off traffic behind you plus the BSFC is less efficient at loads below a certain level) and even if you learn a good habit for say driving on familiar mostly flat roads, if you travel and end up in hills the same strategies may not apply the same trying to accelerate uphill for instance. I would think a realtime BSFC map would be ideal, especially one taking partial throttle loads into account. (I have to assume at half throttle the figure changes slightly at a given rpm and load, just like other aspects like torque change) For that matter a realtime torque curve display, depending on throttle. Or other graphics that might be useful for helping the "human computer" decide how much throttle to use and when to shift, something a little more complicated than the "shift now" light on most cars. In heavy traffic where I can't drag my rear it could still provide assistance to suggest how to accelerate more efficiently under those conditions. Or maybe i'm towing a small 1000lb trailer and that totally changes the physics of the car I was used to driving in a certain way before. Or I have a couple kayaks on the roof rack throwing off the aero but affecting weight minimally. There's so many variables that it's really more in the realm of the computer. And since carputers and cheap LCD's are available now it shouldn't be that hard actually to make something. The main questions are to figure out before anything what data is actually the most useful, beyond the realtime MPG display. The realtime MPG display is great for highway cruising under all loads because it accurately represents what you will be using. It does not give terribly useful information for "pulse and glide" calculations, varying highway driving conditions (unable to pass or set a steady state), nor in town. So what could we do to improve it?