Not sure why you think C4 comes with the HUD, but rest assured the 1999 Xsara Picasso didn't. I drove it for many years and it was fine. Glancing down at the behind-wheel display is equidistant to glancing right to Model 3's (which has the important bits in the same position, perhaps even closer to the driver, then Picasso did).

It'll be fine. Don't judge it before actually trying it for yourself.