Hi, Guest
Right from optima's site! Ignore it if you want...its your coffin.
Trunk/Interior Mounting – If your battery is mounted inside the passenger compartment or trunk (common in many European makes), the battery must be vented to the outside of the vehicle. OPTIMA group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose.
Trunk/Interior Mounting – If your battery is mounted inside the passenger compartment or trunk (common in many European makes), the battery must be vented to the outside of the vehicle. OPTIMA group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose.