are they saying it was in the boot/trunk when it went off??? are they saying it was in the boot/trunk when it went off???They’re saying that’s where the bottle was stored. The only remotely plausible theory is that the decomposing peroxide produced a dangerously high build-up of oxygen in the car and that’s what ignited. However, that really doesn’t sound plausible to me, when we’re talking about a small bottle in a concentration intended for direct use on hair. And neither trunks nor passenger compartments are airtight, limiting the potential for concentrated build-up of oxygen.