Complex sentence: When the German military took delivery of the first vehicles, they immediately put them to the test on-and off-road in snow and ice to test their capability at handling European winters; several four-wheel-drive vehicles were used as reference points.
Split into simpler sentences: When the German military took delivery of the first vehicles, they immediately put them to the test on-and off-road in snow and ice to test their capability at handling European winters. Several four-wheel-drive vehicles were used as reference points.