I only have the 4.1 speaker setup, but had an exchange on the UK Facebook group with a guy who happens to be a sound engineer - here's what he said:
A 3 band EQ is never going to give you much to play with, would try using the EQ settings on your phone if possible.
[in terms of the car EQ], I think from what I played around with the other day:
Bass = 250Hz Low Shelf
Mid = 2kHz Notch/Bell Filter
High = 10/15kHz High Shelf
I would start by playing around giving little boosts/cuts at 63/100/400/1000/8000/16000 whilst playing a track you know well, if you get low end distortion cut a little bit of 32
A 3 band EQ is never going to give you much to play with, would try using the EQ settings on your phone if possible.
[in terms of the car EQ], I think from what I played around with the other day:
Bass = 250Hz Low Shelf
Mid = 2kHz Notch/Bell Filter
High = 10/15kHz High Shelf
I would start by playing around giving little boosts/cuts at 63/100/400/1000/8000/16000 whilst playing a track you know well, if you get low end distortion cut a little bit of 32
