ダンプカーと正面衝突したタクシーはぐしゃぐしゃになった。

。

The taxi crashed head-on with a dump truck and was crushed to a pulp.

Literal

Dump-truck [with-と] head-on collision-did taxi [topic-は] crushed-crushed [became-になった].

正面衝突 'head-on collision' is a four-character sinitic compound of the transparent 'front surface + collision' type common in news writing. ぐしゃぐしゃ is a state mimetic for 'crushed / crumpled / mangled / a mess.' ~になる 'become X' frames the resulting state. した正面衝突 is a relative clause modifying タクシー.