possessives - Should I use "vehicle" or "vehicle's"?

Here are my constructions:

1. Only minimal signs of corrosion on the vehicle body surface which have been removed.


2. Only minimal signs of corrosion on the vehicle's body surface which have been removed.

So my question is, should I use 'vehicle body' or 'vehicle's body'?

Answer

Since OP is effectively using body as an attributive noun (noun functioning as an adjective - in this case modifying the explicit noun surface), I think it's more natural to echo the same usage with vehicle. But this is just a stylistic preference.

In principle, it's even "grammatical" to refer to the vehicle's body's surface. But using two consecutive possessives like this is generally seen as "awkward" from the native speaker's perspective.

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If we consider a simpler case with only one modifier before the noun...

1: The car windscreen is badly scratched

2: The car's windscreen is badly scratched

...native speakers would normally use the possessive (#2) if context implies the need to distinguish it from some other windscreen (The truck is okay, but the car's windscreen is cracked). If that's not the case they'd probably use the attributive noun (#1). As a "rule of thumb", using the possessive in such contexts places more emphasis on the modifier, rather than on the noun itself.