Dash mount stress meter

Dashboard mounted graphic meter showing your current stress level and reminding you to calm down a bit. The sensors would need to be in the steering wheel as it is the one place your exposed skin touches. The device would have to be calibrated for each driver, simply rest your hands on the wheel when in a calm state, then press the calibrate button. Often I find myself stressed or tense while driving and don't even realize it, this way I will be warned when I glance down at the guages (almost out of gas, no wonder my stress meter is through the roof!). Perhaps when the meter pegs a red light comes on on the roof of the vehicle to give others a chance to move away.