You can use smaller less expensive controllers for small cars
that use under 100 volt battery storage. Now, as with
everything you get what you pay for so the smaller
controllers are very limited. You can expect slow acceleration
and perhaps not as good of performance as the units
designed for over 100 volts.
When you get into this range the performance goes up, but
so does the price. Handling up to 1500 or 2000 amps during
acceleration draws a lot of current, these controllers will
handle speedy accelerations rivaling the heaviest footed
drivers on the road today. They are fast.
If you think you are building a slow old clunky golf cart here,
think again. Top speeds can go up over 100 mph if you want,
but are usually governed to the 60 or 75 mph range for
safety.
You can be sure that in town, you will not be left behind at
any stop light, that is for sure.