Found this in the YouTube comments and it worked for me!!! Only thing my light bar is not as bright any more... meh game is now playable. Only Rage crashes time to time, or full game exits sometimes I think it's ELS. We had same problem with GTA IV, soon as we got ELS game started crashing. But it's like drug you can't stop using it! If you have a (small) additional setting to make light bar bright again let me know. Well... hope I can help someone else here it is:

 

The CPU Vertical Sync method helped a lot. I have a Athlon x4 860K, 8GB RAM, and HD 5770. My graphical settings are DX10, 720p, FXAA off, 60% population density, 30% distance scaling, normal texture, very high shader, very high shadow, Ultra reflection, very high water, normal partials, sharp shadows, normal post FX, 16X anisotropic. Drops to around 30 trafficking, 40s + when not moving fast. Small spots will be half loaded for a second every now and then, and some street utilities (stop signs, etc) will pop up when I get close every now and then. Otherwise, helped a lot. :)

@antiboy6 Do you have an issue with too many ELS vehicles spawned in? I tend to have an issue where when I have over three or four spawned in at once I crash. I have to use the add-on CHP and NYSP pack as I can't replace cars because they'll spawn and soon it's too many and I crash. This happen to you at all?

I have almost all real cars (hunt the unchanged ones during patrol HAHAHAHA) No to me it happens random (even parked waiting for calls) or... during high speed chase no other units called yet. but I know it's ELS. All patrol cars are ELS compatible. I want to go back to ELS on my payroll car only, cause in don't like the sirens the AI arrives on scene with. But with the above setting I'm able to get 1hour gameplay or more.

Found it!!! Set normal post FX to High. In order to get the coronas working with the settings I posted earlier. Below is the fixed one. 

 

The CPU Vertical Sync method helped a lot. I have a Athlon x4 860K, 8GB RAM, and HD 5770. My graphical settings are DX10, 720p, FXAA off, 60% population density, 30% distance scaling, normal texture, very high shader, very high shadow, Ultra reflection, very high water, normal partials, sharp shadows, HIGH post FX, 16X anisotropic. Drops to around 30 trafficking, 40s + when not moving fast. Small spots will be half loaded for a second every now and then, and some street utilities (stop signs, etc) will pop up when I get close every now and then. Otherwise, helped a lot. :)