Over on the Xebra_EV mailing list at yahoo!groups there is exciting news... One of the Xebra dealers had an inspiration that has led to a modification to run them at a higher voltage, gain greater speed and better range.
They are working on several ideas and something good is coming from it. The link above is to one of the core messages but if you're interested you should read the other messages in the thread.
The stock Xebra has a 72 volt battery pack and an Alltrax controller. The modification is to add another battery, making it an 84 volt pack. The motor is able to handle this fine, and it turns out the Alltrax controller is also able to be overvolted (They're working with Alltrax directly) because it uses components spec'd at 100 volts.
- David Herron, http://www.7gen.com/