What is the main difference between SRAM and DRAM in the automotive industry?
A simple SRAM cell is 6 transistors, and then you have something called "charge" amplifiers at the top and bottom of a column to "throw" the signal hard one way of the other.  

A DRAM cell is two transistors, and a trench capacitor; however, you need to refresh it as it leaks down.   DRAM is more dense than SRAM.

There's actually a balance between speed/density and which one you would use.  External RAM is almost always DRAM, and internal cache has been traditionally SRAM; however, I use DRAM as cache when I have greater than 16MiB of cache because the total power is lower even with a refresh.   DRAM starts at a higher power, but the increase in power on a per-bit basis is slower than SRAM.  SRAM starts at a lower power but the total increase in power on a per-bit basis is higher.

This document will give you some answers on what this looks like for IBM (now GFs) processes:  http://www-07.ibm.com/tw/imc/seminar/download/2010/TW0AL02M-02.pdf