The 135’s disconnect is mounted on the passenger side off of the roll cage, right about at the height of the base of the passenger door window opening. There’s a standard lightning sticker on the outside of the car on the passenger door to signal to a corner worker that, in an emergency, they can find the disconnect near there.
In my personal opinion, all emergency features should be on the driver’s side of the vehicle. A corner worker is going to want to check on the driver’s status immediately, so having all features there would be preferable. This would include an exterior-accessible fire system actuator in addition to the battery disconnect. The 135i does have an exterior actuator, it’s just in a different place.
For extra super duper safety, controls on both driver and passenger side would be optimal, as it's entirely possible the driver-side of the car might end up lodged against a barrier. Corner workers are a pretty adventurous bunch, and will likely dive in through a passenger window to hit the driver-accessible controls.
But, I’m just nitpicking an otherwise great build.
Don’t forget that, with a battery disconnect, you don’t want to just disconnect the main battery feed. You also have to ensure that the alternator charging circuit is disconnected from the electronics-side of the car. Otherwise the engine is spinning, turning the alternator, which is generating sufficient voltage and current to run the car! If your disconnect doesn’t kill your car, that’s why.
85,669 miles? I wonder how many of those are on the track and the dyno…
You can just make out the fire system pull on the lower right of the frame. You can also see the passenger-side Schroth safety net and its buckle hanging.
An interesting feature on the Ergo is that the head protection system is actually removable.