One Question: Why?
There are so many things wrong with what I'm playing here. I'll put it down to four for you.
1. You're doing this as an advertisement for a radio station, BBC Radio 1 I'm assuming, yet rather than taking the obvious and sensible route in making a rhythm based game you made a racing game with DJs? Why? It doesn't show anything about their music or the station so what's the point?
2. This game was made in flash, an engine built more for artistic quality than gameplay quality, yet you attempted to make a mode 7 game with a jumpy camera and poor sprited graphics... Flash games are made purely to be fun and usually that fun comes from chaotic and nonsensical gameplay with colourful and simple graphics, not a cheap looking Super Mario Kart wannabe.
3. The challenge system is ridiculous! For one thing, all the times you have, for the first course at least, are either bunched together in scores too high for noobs or WAAAAAY too easy for even a 6 year old. The #1 and #10 best DJs had a difference of 4 seconds, most of the lower scores come at around the 50 seconds to 1 minutes zone and I even saw one with a score of 2 minutes 35 seconds! Who manages that? If you can't get a proper array of scores to beat why didn't you make some up?
4. The DJs you race with a retardedly unbalanced. How can the fastest kart also have the sharpest turn? Why is there somone who can just fly over the grass between checkpoints? Why even bother having three normal karts when it's so obvious Fearne and Zane are overpowered?
Nothing about this game works! This could quite possibly be the worst advertising game I've seen since Dash of Destruction. I can assure you this game has given me no reason to listen to BBC Radio 1. At all.