I use an Arduino UNO, and I want to build an RC car with four DC motors [Johnson-39180 3A4362] and control each one separetly...the voltage from the arduino is too low with four motors, even using mosfet transistors and diods. I tried to use an H bridge with the chip kit from arduino but i don't find the electronic configuration with four motors, only with two...
if someone is so gentle to answer with an image or an electronic plan, i'll wait.
P.S. sono italiano, se qualcuno potessere rispondere in italica lingua sarebbe meglio 
You need two dual-H-bridge drivers. However, I can't find those part numbers on the Johnson Motor site; and I can't advise on which H-bridge is suitable without knowing the motor specifications. Can you provide a link to the motor datasheet?