Complex sentence: The W180 was the first in a series of Mercedes-Benz models to receive the "Ponton" moniker in reference to the pontoon-shaped exterior styling, a style which the later W128 line also featured.
Split into simpler sentences: The W180 was the first in a series of Mercedes-Benz models to receive the "Ponton" moniker. This was in reference to the pontoon-shaped exterior styling which the later W128 line also featured.