The desk top is pretty big. I think we had to put the top down in our Cabrio in order to get ours home. You might be able to get by if you can put the passenger seat all the way down or something.
The Galant desk is basic but effective. My fiancée got the version with the motorized lift on closeout, so she can work sitting or standing. Too bad they apparently don't make it anymore.
Ikea is definitely the best of all the "cheap" options. The office superstores and Target don't really have much good stuff IMO. EQ3 has some decent items, but they don't have a whole lot of stores in the US. Love BluDot, but their stuff is pretty spendy. I wasn't all that impressed with CB2: seems like a slightly more upscale Ikea, at best.