Instead of looking for a processor that can handle the reasonably easy tasks of pedal position etc. you should probably be looking for a processor that can track the engine position. The coordination of the crank and cam signals and scheduling of spark and injection is, by far, a more complex task than reading an ADC to get slowly changing analog values.
ST, along with NXP, make a line of processors that handle this segment (SPC5). Not only are those processors temperature rated for automotive use, but also designed for these safety critical installations.
You COULD use an STM32 for the task, but you'll quickly run out of timers. Others, like MegaSquirt, have used non-automotive targeted processors and, with enough work, you can too.
