How fast can the MINI-Z go?

Well, the top speed depends on models and settings including batteries, motors and gearing.

For example, the MINI-Z MR-03 VE Pro, one of the fastest MINI-Z, can go about 35 km/h with the standard 8500KV brushless motor and 4 x AAA NiMH batteries.

This video made by JB3 RC records 21.9MPH (35km/h)  with the standard MR-03 VE PRO: