Go for a 4-wire sensor or you can end up with inaccurate readings due to the volts drop developed across the engine earth strap, as the alternator charges the battery or when you have the head lights on!!
You can go one step further and fit an isolated 12 volts supply to the meter/sensor.
This isolates the ground loop affect and will make the meter as accurate as it can be!!

Cheers.

Steve.