Not a good idea!
It will generate some electricity but the efficiency will be very low compared to other methods.
As hameeds01 states, getting it to rotate fast enough is your first problem. If you think of how the generator is mounted in a vehicle, normally it is driven by a belt and small pulley. The small pulley wheel is to achieve a speed increase over the engine RPM. At low revs, the generator will not work well, best efficiency would be in the region of 6,000 to 8,000 rpm and a wind turbine would only manage a few hundred in a strong wind.
The other consideration is that vehicle generators have field coils instead of permanent magnets so you would need an energizing current before it would start at all.
Some people have experimented with vehicle generators by dismantling them and replacing the field coils with permanent magnets but it isn't easy to do and even if you can manage it, the efficiency is still lower than other 'home made' types.
Brian.