This ENB config will improve reflections for vehicles, vehicle glass and vanilla vegetation models. 
If you use patch 4 (1.0.4.0) this ENB config will also improve reflections for blood and
reflections for the ground for any kind of rainy weathers, night lights and vehicle lights.
It doesn't add other typical ENB shaders/effects like bloom, adaptation, lens flares, AO, clouds and other things. Just the upper mentioned things.
You also have to expect a little performance lost of 2-4FPS.

Installation:
Put the files from the "Files" folder into your GTA IV main folder.