That would be ideal. I was originally looking into an older honda boss, or a ruckus. Fairly cheap, fairly light, and so on. Figured I could do something much better for the price though. Bionx has my eye so far, especially with the 500 model.
ok so here is the skinny to go faster you need more voltage ie most companies sell 36 volt batteries as part of their kits and the top speed is about 30 to 35km/h. Some systems (thru the controller box) limit the speed to 30km/h some don't. I had a 48 volt battery and I would reach about 45km/h at full throttle.
To get distance, you need amp/hour. Every battery is rated for how much amp/hour it can produce. a 36v 10 amp should get you about 20km if you have stop and go and some hills. That will diminish by about 10 to 20% if it is below zero celsius as batteries and conditions affect the range. my 48volt 10.5 amp/hour got me home and that was 23km with hills and some stop and go with a little power left even in very cold weather (coldest was minus 17 celsius)
The last part is having a system where you can throttle separatly than your pedaling as the bionx system only engages if you pedal and there is a delay when you do, i find it very useful to be able to separate both.
why cant you just use a road bike? can get one with a flat bar and mud gaurds maybe...
too much snow and skinny tires don'go well together. also I used to commute with a cross bike but after 45 minutes, I would get cold no matter what I was wearing. now 45 minutes is what it takes and I still exercise