Although the robot car must be designed mainly on FPGAs, you can also use hardcore processors inside FPGAs (e.g., Xilinx Zynq, Intel Altera SoC) so that you can use a lot of ROS applications for your design.
(*) Application and paper submission deadlines: September 15, 2018.
However, you can continuously develop your car until December 11, 2018.
You still have much time for developing the robot car with ROS/FPGA!!
Could you try on the design competition?
If you have any questions, please send an e-mail to "watanabe.minoru[at]shizuoka.ac.jp".
(Please substitute @ for [at]. This is the contact person of FPT2018 FPGA Design Competition Chair, Prof. Minoru Watanabe)