The AT-4 is an autonomous passenger vehicle that operates throughout GLMZ's upper and middle tiers, providing on-demand transportation to subscribers of Vantablack's mobility service. The vehicle seats four passengers in a windowless, sound-insulated cabin with interior environmental controls and entertainment displays. There is no steering wheel, no manual override, and no way to see outside except through the vehicle's own camera feeds displayed on interior screens — feeds that Vantablack can modify in real time.

The Phantom Cab's most controversial feature is its routing algorithm. The AT-4 does not take the fastest route, the shortest route, or the route the passenger requests. It takes the route that maximizes Vantablack's revenue, which may include detours through commercial districts where the interior displays show targeted advertisements, or past competing businesses whose negative information Vantablack has been paid to present. Passengers in a sealed, windowless cabin with no manual override are a captive audience in the most literal sense.

Vantablack's terms of service — which no one reads — include a clause granting the company rights to all conversations, biometric data, and behavioral patterns recorded during transit. The AT-4's cabin is the most surveilled space in GLMZ per square meter. Business negotiations, personal confessions, medical discussions, criminal planning — everything said in a Phantom Cab belongs to Vantablack. The company's data brokerage division generates more revenue than its transportation service.