Shock and vibration in cars

I have scoured the net for hours and cant find the information I need. I would like to know what are the (APPROX!) ranges of shock and vibration produced by road-driving cars.
I understand that different cars/road surfaces produce different result, but I have no clue as to the levels of S&V produced in a car, in the given units (G/ms, G/Hz).
Does anyone know of a resource which provides any information related to this, or can give me some rough guidelines.
My dissertation involved designing a system which will operate in a car, however I need to consider (and justify) whether it can operate under driving conditions (although I 'know' it will be fine, but must compare my products resilience to V&S in the report)
Thanks,
Nick