I had a dark problem here, so I used raycomptex to save, copy the Env_Main and rename it as "Env_Side", set Env_Side as the second subtexture of the vraycomptex, then rotate the HDRI to a right angle (Fig.49).
By doing this, I had solved the dark problem. Once I was comfortable with the angle of my HDRI, I adjusted the overall mult and gamma one by one to create a beautiful environment. This is a useful skill, especially in outdoor scenes (Fig.50).
So, I had finished the environment now and it was time to start setting the lights. Lights are used to enhance the performance of an environment (look at the surface near the tail light; it was too dark at this point). Because I had created diffuse illumination and environment reflection by IBL, I only needed to create specular illumination this time. I made a special script to do this job; it's a standard direct light that had the highlight place function.
The first job in the specular process was to match the environment highlight. To create a specular light, I clicked the target position in camera view, so that the light would find a proper position (place highlight). Adjusting the light's position and scale helped me to get a better view (Fig.51).
I then created more specular lights, to make the tail light area better, before getting a final render. In the Render Elements, Reflection, Specular and Refraction were the basic channels (Fig.52).