The warranty terms aren’t saying they won’t cover any car that’s been modified.
It’s saying it won’t cover if the failure is caused by/ arises from or is connection with the modification.
Seems reasonable to me.
It would make more sense if that is the case. However, is that really what it’s saying? The wording of the exclusion is;
This cover does not cover any injury, failure, loss or damage caused by arising from or in connection with Vehicles modified in any way from the original manufacturer's specification.I interpret that as meaning if a vehicle has been modified, then any failure, loss or damage to that modified vehicle wouldn’t be covered, irrespective of whether or not it was caused by a modification. If the exclusion is intended to just exclude failure / loss / damage arising in connection with a modification, wouldn’t it be worded along the lines of the following?;
This cover does not cover any injury, failure, loss or damage caused by arising from or in connection with Vehicles modified in any way from the original manufacturer's specification where the failure, loss or damage is a consequence of the modification(s).
This is just my opinion though
. I do agree with @sjw on the point they make regarding enforceability.