These days, most four-wheelers are easily able to reach pretty high speeds, even with stock settings. Most of the faster ATVs out there could reach the high-70s to low-80s mph. If you're crazy enough to modify an ATV and add rocket thrusters, you might even be able to just barely reach under 200mph. Regardless, Can-Am makes some of the fastest ATVs on the market today. Its Commander four-wheelers, for example, tops out at a speedy 75mph. The same goes for the Outlander 1000, which is capable of easily reaching similar speeds in the high 70s mph. Although, if you remove the limiter with an ECU flash, some have even breached 83mph in an Outlander 1000.