The guy on the stall said they're coming out in 16x8 & 15x10 later on this year too.
They're certainly nowhere near the same build quality or strength as Mach 5s but they sure as hell look the same.
And as BGB said - the spokes aren't completely tubular - they're flat at the back, so anybody looking at buying a set of second hand Mach 5s from eBay etc should take note and bear this in mind, as this is about the only way to tell them apart when a tyre is on the rim, although you could search for the seam weld going straight across the width of the rim too, I guess.