As the number of electronic components in the car increases, the requirement for the higher data transmission scheme among them is on the sharp rise. The control area network (CAN) has been widely adopted to support the in-car communications needs but the data rate is far below what other schemes such as Ethernet and optical fibers can offer. A new scheme for enhancing the speed of CANs has been proposed, where a carrier modulated signal is introduced on top of the existing CAN signal, whereby the data rate can be enhanced over 100 Mb/s. The proposed scheme is compatible with the existing CAN network and accordingly enables seamless upgrade of the existing network to support high-speed demand using CAN protocol.