Vehicles including split-bus architectures are disclosed. An example vehicle includes a bus and a firewall. The bus includes a first zone, a second zone, and an I/O backplane. The first zone corresponds to an untrusted environment. The second zone corresponds to a trusted environment. The I/O backplane is configured to provide power to one or more devices connected thereto. The firewall is connected to the first zone, the second zone, and the I/O backplane. The firewall is powered by the I/O backplane. The firewall is operatively positioned between the first zone and the second zone such that a first operative side of the firewall corresponds to the untrusted environment and a second operative side of the firewall corresponds to the trusted environment.