OLED screens will offer higher resolution, more color range, faster response time, and less power draw. all great improvements over LCD panels but it will still be a while before a small pc screen (VGA or better) is available as a standalone item.
I can certainly understand why it would be a better carputer display
but why do you think it will make fabricating any easier? it will take just as much effort to build an OLED display into the dash as it does to build an LCD display into the dash :/