There are a couple of ways to lower the vehicle. Probably the most popular now is the use of air suspension, since many of the high-end models that are modified into VIP cars already come equipped with air suspension. Since factory air suspension won't allow you to lower the car enough, many enthusiasts install a special air control system. Coilovers can also attain the desired lowness. Try to minimize the distance between the wheel and the fender. Edit if you are a purist coilovers are the only way to go. A true VIP car uses coilovers only, and airbags are looked down on.