Which is better of thees CPUs:
Cortex A53 octa core 1.5 ghz,
Cortex A7 Allwinner T8 Eight core 2.0 ghz,
Cortex A9 Quad-Core 1.8 ghz ?
Better in which respect? Power consumption? Speed? Performance? Why do you ask? Or, better: What do you expect as answer?
They are used in android car Touch Screeni'm looking for the best performance.
Cortex A7 and Cortex A9 belong to 32-bit ARMv7 architecture.
Cortex A53 belongs to 64-bit ARMv8 architecture (next generation).
If you want only best performance choose Cortex A53.
But overall performance of the system depends on different features like who manufactures the main processor, how many peripherals embedded in System-on-Chip (SoC), what kind of Operating System is installed and how it uses all features of the SoC.