Did I damage my undercarriage?

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I’m assum;ng you are certain yo didn’t hit the spike with your tires. If you think this a possible that you did, you should have your tires inspected straight away as it would be a safety issue.

Suggest as mentioned by VDC that you keep a check on the car’s fluid levels. Oil, coolant, brake fluid especially. Those are usually easy to check just by lifting the hood. Keep your nose on the problem too. Gasoline — evenn in small amounts – is easy to smell.

It’s totally possible little to no damage was done. Most newer cars have center engine mount brackets, and that might have taken the hit and bent the spike over before the rest of the car went over. But you’d have to be a little lucky too. Maybe that was your lucky day. If everything seems fine and nothing’s leaking and the car runs as before, suggest you ask for a visual inspection the next time you have your oil changed. Now may be a good time to do that if it is coming due anyway.