Can FPGA-based ASIP be used in real life?
You can get automotive-qualified FPGAs.  There should be no issues so long as you get one that will work over the temperature range you need and you design the support circuitry correctly.  An ASIP may be faster if you build it in silicon, but if the FPGA implementation is fast enough, it's not like it's going to suddenly get slower when you put it in the car.  The main 'con' is probably going to be price, but if you're only making a handful then it might be far more reasonable than going full custom.