Possible Clues:

• Hit from behind
• Didn't stop behind in time
• Hit from behind ... and what the answers to starred clues are?
• If you clipped all of grey car's fender, driver in front would be ____-_____
• Bumped from behind, or a hint to 17-, 25-, 37- and 48-Across
• Ran into river and finished after repairs oddly ignored
• Slammed into from behind
• Rammed from behind
• Ran into on the road, or an apt description of 17-, 23-, 36- and 49-Across