although, this was posted two months ago, I am still going to reply because no-one else has and it may be good for other people who have this same question, which I bet will appear 100 times on these forums LULZ...
Ok, I say that you should start off by finding good ref. images. (
http://www.suurland.com google.com) Then look at some tutorials. They are so MANY tutorials on car modeling that with a quick google search you will find well over 100 search page results...thatsa lotta links LOL... When you want to make a futuristic car, look at some sci-fi spaceships, and work them into cars (Don't know if that is really clear or not) then if you are a complete and total n00b, block out everything that is said above, and figure out how to use the UI (User Interface) of the program u are using.
-CP