Hitachi and Honda have teamed up to prototype a "portable alcohol detection device" that might be integrated into your next car's key. You can't fool it by spraying air on it -- it knows what human breath is -- and it'll work even when it's not near your car, giving you the ability to check your sobriety even while you're still sitting in the pub.
Most in-car breathalysers -- which function as an ignition interlock, stopping the car from starting until a test has been successfully passed -- are directly linked to the car's ignition, meaning the test has to be taken while sitting in the vehicle. Honda's battery-powered smart key can run its tests anywhere, reducing the car owner's temptation to drive drunk.
With a small display on its body, the Honda and Hitachi key can give a graphical read-out of the driver's alcohol blood level, with a 5mm-square sensor able to distinguish blood alcohol from a breath sample to a sensitivity of 0.015mg/L -- so with several steps of sensitivity underneath and above Australia's 0.05mg/L national drink driving limit.
Hitachi and Honda demonstrated the tech at the SAE 2016 World Congress, but there aren't any plans just yet to integrate the system into a production car just yet.