In short, no, you can't change the number order of your axes. You can change the scale (logarithmic, for example), and you can change the label displayed (plot by index but display whatever you want as the label), but you cannot have dicontinous values in an axes.
m = 100;
v = [30 20 50 70 30 0];
y = 0.5*m*v.^2;
plot(y)
xticklabels(v)
figure
bar(y)
xticklabels(v)
If there is a way to turn your velocities into a continuous data series, that might provide a solution. Perhaps elapsed time of your trip? Something that orders your velocities the way you want.
