Yesterday a guy asked me for a jump, old boy who had filled his Ford F-150 then couldn't start it. I was driving the wife's Kia Stinger, all I've done in the engine compartment is add bug spit. So I pull straight into his truck, pop the hood and lo and behold....no battery. So, even though I suspected it was in the trunk I got out the owners manual and this is what I had to remove to access that battery.
Carpet, inner spare tire panel, spare tire with jack etc., positive terminal cover (good) and it was under all that. I swear looking in the engine compartment I will never work on that car!