>>>If he's also charged with taking the car without consent what's the penalty for that
As I wrote above:
"Taking a vehicle without consent does carry a possible prison sentence (of up to 6 months) but such a sentence would normally be reserved for (say) repeat joy-riders and would not be imposed upon someone taking a vehicle from a family member.
Your friend won't go to prison."
To read exactly what the magistrates would be required to refer to, see page 110 here:
http://www.sentencingcouncil.org.uk/wp-content/uploads/MCSG_web_-_October_2014.pdf
You'll see that, in the circumstances you describe, a prison sentence can NOT be passed. If the offence was seen as being at the very lowest level he could just be fined. Otherwise a Community Order would be imposed.