Can you tell if the copper portion of the cable is thinner? Or perhaps just the insulation is thinner?

Improvements in insulating materials has made some of them to be thinner. This has caused concerns when wires are pulled through conduit that the thinner insulation may not hold up to the abuse of pulling the wires.

Can you see if the strands in the cable are the same size as the originals? Finer strands could carry electricity better.

Perhaps Volvo overbuilt the original cable, although your original cable failure does not help in thinking that!.