I like Maz's idea of using one of his foreign names. In Chinese he's 大黃蜂 dà-huáng-fēng, which means 'hornet'. The 3 characters literally mean 'big yellow wasp/bee'. Or you could go with what he calls himself in the Bay movies, 'blip bleep bloop'.
My favourite tool is TFU.info's 'ID your figure' feature, which sorts toys by colour and alt mode. As for yellow cars, you're not short of options. Personally I'd go with Freewheeler, as it's unlikely to clash with anything else.
If it were me, it'd just be Bumblebee from an alternate universe. That said, you can always slap some Decepticon symbols on him and call him Decepticharge.
thanks everyone for your suggestions. While Bumblebea Arthur rocks, the name Hornet stands out to me and I think that's what i'm going to go with!