It comes with heated front leather seats which are £1600 option, which brings the price difference to £900. The yellow is actually metallic, which you have to pay £495 for, so the extra for yellow is £405 over standard metallic.
You can also have the bonnet, roof and boot decal for free, which have a combined cost of £380.
So, if you wanted heated leather seats and metallic paint anyway, its costs £405 on top of what you would pay, which is cool as its a special colour and only 86 are in the uk.
If you wanted the decals as well the extra for yellow and a limited run is only £25.
Pretty good deal for either.