Addressing urban congestion through enhanced traffic capacity has emerged as a critical objective for connected autonomous driving technologies. An irredundant communication connectivity topology is essential for ensuring the high efficiency and stability of the traffic system, which has not been fully validated due to the scarcity of real-world tests. Motivated by this fact, this paper deploys a connected autonomous vehicle platoon without relying on the information of a platoon leader to preserve the possibility of extending the platoon in future practical applications. The study is supported by both real-world experiments and simulations, where the following vehicles communicate with the two vehicles immediately ahead. The simulation extends the experimental results to several typical scenarios. The results demonstrate that such a communication structure largely enhances traffic capacity and stability, highlighting the effectiveness of connected autonomous vehicles in managing complex traffic environments. This work gains valuable insights into the sixfold traffic capacity improvement through connected autonomous driving.