It's usually a months interest as penalty for early repayment. There might also be a final payment fee as well couple hundred quid.
For example if a 1000 payment is at 8%, pay 80 extra. Plus a final value fee. Total cost maybe 300.
As a very loose example!
So you're actually better to take a very long finance term in this case where a months interest will be less money due to the lower monthy cost.
Someone correct me if they know better.
Previously: 2003 Peugeot 206 1.6 8v | 2006 E90 320d M-Sport, 19" BBS CH, Full Ice-cold JL audio install, August 2010 Total BMW 6 page feature car. | 2003 Nissan 350Z GT Coupe 286BHP
Now:2010 E92 LCI 335d M-Sport