GEM dreams

Bought a 2008 GEM S2 with the intention of using it to run to the grocery store, out to dinner and down to the beach is our small community of Apollo beach, Fl. The posted speed all over town is 35 MPH. Darn near got killed the first time I pulled out on the main Blvd. The speedometer shows that wide open I am traveling at 15 mph. Checked it with wife following in car and it was right. 15 mph top speed on level ground. Yes, i had it in road gear. The batteries are new and have been load tested. They are okay. I thought I would see 25 mph tops with factory settings. I have the 7 hp factory motor. Plenty of torque but not enough speed. Any Ideas???