I don't get frightened by speed at all, but as mmm comments spend a lot more time scanning the road, anticipating where an danger could arise., etc. I'm relaxed, but focussed and in control, but my mechanical sympathy does increase dramatically as minor bumps on a road at 30 can become spoiler damaging crunches at speed and so on.
Actually the only time I get really scared is some of the extreme off road events an that's at 10mph, but the consequences of sliding off mountain ledges down sheer drops, into ravines, driving downhill on sheet ice, etc. are not only a wrecked Jeep to recover but serious chance o injury. Hey but the buzz is amazing...