Car finance rates - expensive or is it just me?

[markrtw]

I fancy updating my car in the near future and surprised at the interest rates dealers list for their finance. Looking at say a 2016 golf gti PP from main dealers they are typically asking 9.9 - 12.9% which seems extortionate to me (though not quite wonga) with the base rate being what it is. Nationwide's loans are 3.4%. (1st place I looked at without searching the market for the best deal). That makes the repayments lower than having a PCP and no balloon payment and much less to repay overall.
They must sell a load of these packages, but why do people favour them? I can see that it's a way of financing something that's a lot more than you can borrow from a bank, but a 15k loan and say 6k cash/trade in, you can get a lot of car. Or am I missing something?

[Taaaaang]

Dealer finance is easier to get than an unsecured loan, hence the higher rate.