gsm modem project urgent help

hello
i m making project using gsm modem
i m controlling car through mobile
i m facing difficulty in designing the hardware
i m using 4 relays for each function
for start stop lock and unlock each relay respectively
could any design circuit for me
or any help ....i don't know what more hardware components should we use
using the microcontroller as well

Try integrating a DTMF receiver(like MT8870) on the audio output of GSM modem. There are many other solutions out there.