Designing a PWM DC motor controller for under a car hood...

Hello all,
I am designing an open loop PWM DC motor speed controller for a 12vdc
pump. It will reside in the "harsh" environment of under a car hood.
The motor speed/PWM output will be controlled by a sensor CV (0-5v).
Motor requirement is 12vdc / 3amps continuous (6amps@start). My
question is whether I should lean in any of these following
directions...

1) 556 (Dual timer circuit) driving a MOSFET
2) LM324 quad opamp circuit driving a MOSFET
3) Some type of dedicated motor control IC

There will not be a microcontroller in the system.

****
So, I know that 1 & 2 above will theoretically work, but will the
control voltages be susceptible to the "harsh" noisy environment? I am
a PCB designer, so designing a PCB with proper noise rejection is not a
problem. I am leaning toward #2 above...but I wonder if it would be
smarter to find a dedicated motor control IC that has protection
circuitry built into it (over temp, over current, etc). Lastly, the
LM324 is pretty wimpy on the temperature range, so I would probably
need to use the military LM124 which is waaaaay more expensive. Target
price for the electrical system is <US$10 (not including my sensor).

Any advice would be appreciated.
thx,
frenchy

.

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