There can be several causes. If overheating, you will have a more whitish smoke mixed with steam. Do not just put water in the reservoir...you will need to use anti-freeze, but you will also need to have your thermostat checked out.
If its greyish/blackish smoke, you're burning oil and you most likely have a broken head gasket or valve...both of these conditions are indicative of the worst case scenario.
Also, don't forget to check your tire pressure every time you refuel.
I agree with e46...park the car immediately.
There can be several causes. If overheating, you will have a more whitish smoke mixed with steam. Do not just put water in the reservoir...you will need to use anti-freeze, but you will also need to have your thermostat checked out.
If its greyish/blackish smoke, you're burning oil and you most likely have a broken head gasket or valve...both of these conditions are indicative of the worst case scenario.
Also, don't forget to check your tire pressure every time you refuel.