What does that mean? (6) rigs 100k each? One rig 620k? How many repairs were required, what sort of conditions? I'm guessing most manuf test for millions of miles on any new vehicle but doesn't directly = reliability or longevity, it really depends on what their design parameters are along with their MTBF expectations.
In the case of Ineos - they are using off the shelf products that have design life engineered into them, the engine and trans out of the BMW had longevity test done prior to them getting their hands on them, regardless of what Ineos tested too. Same for axles and any other sourced part since (as far as I know) none of the parts were specifically designed for them and probably fall well within the std. expectations of most modern rigs.
Toyota for instance built LC 70 series using their own Toyota axles, engine, trans, etc....they had full control over design life expectancy / MTBF (or MTBO in the case of the 70) of those items.