GT5 - Unlocking cars in arcade mode ? seriously?

Ok for arcade mode there are already a few cars there,

but how on earth do you unlock the rest? i assumed just like GT4 just as you buy cars it will become available in arcade, but it dosnt.

you can use the cars you bought in arcade by putting it in your favourites list. but then you cant change the colours or nothing like the original arcade cars.

and lets say you want to use a stock ferrari enzo. you cant because your one has engine mods and you cant undo it. for when you wana do time trials around the top egar test track to compare cars. you cant.

so is this really how its gonna be? or will they get unlocked eventually? this is annoying me. because when i finish campain i will be spending time in time trials and things, and i dont want to use my modded cars and what not. so now im losing races because i havnt modded my car, because if i do its modded forever unless i buy another

thanks guys, other than that. awesome game!

eh practice mode would be the same as arcade mode really. all the cars will be modded. i mean it will be cool to use the modded cars you've spent money in in arcade in the favourites section. but you should be able to use the cars as stock too. even in 2 player split screen, cant change colours or nothing. i hope it gets patched up fast

yeah see that was a good point as well. sell the car and its not in arcade anymore. that's rubbish. the system in GT4 was good. you buy the car its unlocked in arcade same way the other arcade cars are.