This is an idea I’ve had for a while – thought I’d publish it here in case anyone can make use of it (or so there’s some evidence of prior art in case someone tries to patent it)
Add haptic feedback to the accelerator pedal of a car that increases the force required to depress the pedal in relation to the fuel consumption. So, if you’re mashing the accelerator pedal down and using lots of fuel, more force is required on the pedal. This way, drivers would have a physical reminder of fuel consumption, which would hopefully alter driving habits.
I imagine this would be fairly simple to implement (the most basic – a progressive spring attached to the pedal – more complicated – a motor introducing resistance proportional to instantaneous fuel consumption) on modern cars with electronic throttle control. This might be a good project for a cognitive psychologist to measure the impact on driving behaviour.