Honestly, a JR pass is a good investment (approx 30,000yen return or get a special for under 20,000 via a tour company - needs a bit of notice). I spent 15,000yen (near $200AU) in tolls in 2 days & I even avoided an expressway due to the twisties. At least 10,000yen each way from Osaka <-> Tokyo. Fuel & parking is also expensive too.
 
Bullet train is a fast trip anyway (smoke/eat/sleep). But then again, road trips are fun if you have a lot of time.
 
Drop off fees are approx 8,000-10,000yen ($100 AU+), sooo not worth it. I got pretty handy with the train system & found my way to pre-booked rental places without much drama (didn't even have a map or 3G access).
 
I ran the numbers too & split 3-ways, it was only fractionally cheaper to drive (compared to train). In retrospect, I'm glad I didn't drive to Kyoto. Bullet train was fun & I didn't waste time being tired & getting lost.

This is my plan so far if you're interested in taking a look. I really appreciate all the help. I'll make sure to do a write up and pictures for the forum.
Wed 23^rd              Arrive Kansai Airpot Osaka at night.
Thur 24^th              Drift tour in Osaka (still need to organise)
Fri 25^th                   Hire a car, see Osaka sites in the morning, and drive to Tokyo in the afternoon. Go to Daikoku car park, then dropcar off at Haneda Airport. Cost of car for one day with drop off fee looks to be $400AUD plus gas and tolls, probably another $100 or more. (maybe I’m underestimating, split between 4)
Sat 26^th            -27^th     Check out Tokyo, List of possible things to check out: Fish market, Harajuku, Shinjuku, Shibuya, Tokyo tower, Roppongi, Akasaka, Rainbow bridge, Toky Bay, Akihabara.         
Mon 28^th           Disney Sea
Tues 29^th          While the others go to Disney land I’ll grab a car and go to Chiba as suggested. Maybe be able to do a 6 hour hire of a car.
Wed 30th         Spend the day driving to Kyoto, early start and check the path to mt fuji and lake ashi as suggested. Car cost same as above, these drop off fees are crazy.
Thur 31^st- Sat 2^nd               Check out Kyoto, the tour suggested maybe, the hot springs, train or bus to Osaka and fly out Saturday afternoon back to seoul.
Why is Japan so expensive haha! The bullet train is an option for the Friday trip and get a taxi out to Daikoku car park, but I think the costs will work out pretty similar.
Anything you think I should add, maybe take out?
The only thing I cant really work out how to fit in there is the Toyota plant tour in Nagoya, might mean I have to go back another time haha.
 

My suggestions/highlights:
 
- First issue I see is that Drift tours are on set dates from memory, so you may not have the luxury of picking a date @ your convenience. If you miss out, you can always make up by renting a nice car. 370Z would be great for the twisties, the R35 needs too much speed & the corners are very tight/slow for it to stretch enough.
 
- Buy a JR pass (prolly cheaper & much less stress).
 
- Take a day tour of Kyoto from Osaka (since it's so close - arrive via JR bullet train), then make your way to Tokyo in the evening. I don't recommend driving a car to tourist sites/spots as parking is an issue (will waste most of your time in Kyoto) & directions/navigation will be hard too.
 
- You can still get your shot at driving when you rent a car & goto Chiba. On that day or two, you can do the Mt Fuji/Lake Ashi drive. Depending on where you stay, I'd just rent a car nearby (plenty around Tokyo & Shinjuku area). There's a Nissan car rental next to Shinjuku station (refer to tocoo site I linked above). Park at your hotel (I parked mine @ Keio Plaza in Shinjuku - where I stayed - convenient!).
 
- Go to both Disneylands.
 
- Scrub off the Toyota Plant. You probably don't have enough time & are better off spending it checking out Tokyo.
 
- For Tokyo, best view of Rainbow bridge is near Tokyo Teleport Station (Toyota Megaweb). Not impressive IMO. For when you check out Shinjuku @ night, scare yourself a bit & get harrassed by the Africans in Kabukicho (redlight district) & get intimidated by the Yakuza presence....lol Fish market is really dependant on if you're a food junkee. Tokyo Tower is a waste of time. Daikoku car park is annoying to get to (only by car IMO) & is really just ricey. After you see the cars in Chiba (Top Secret) & some of the surrounding VIP car dealerships, the kid in you should be smitten enough.
 
- If possible, befriend/pick up a local or two & they may show you an excellent time on the town.
 
- When you rent a car, go for longer than 6hrs. Traffic can be a bit unpredictable (better than Sydney though strangely). Use the opportunity to hit up some places in Tokyo late @ night, as trains stop @ midnight. There's some nice clubs that a bit out of the way by train/public transport.
 
- Near Mt Fuji tourist centre is a theme park (can't remember the name) with a CRAZY looking rollercoast. If it's open, GO!!! Additionally, I hear Edo Wonderland is good too (can catch bus/tour or maybe bullet train). I'm sure your hotel can help you arrange that.
 
- Specific Tokyo spots I recommend you prioritise are Harajuku, Shinjuku, Shibuya, Akihabara, theme park in Tokyo (another cool rollercoaster). Dont' really bother with the Imperial Palace or Shrines in Tokyo if you're going to Kyoto.
 
Above all....Drink plenty of SAKE!
 
Despite what people think, Japan is actually cheaper than Australia if you're smart. You can blow A LOT of money in Japan if you're silly though (like anywhere I guess). If/when you get lost & need directions, compliment the poor Jap you're asking about how nice their country is first (they're very proud). Everytime I did so, they were so helpful they would insist on taking me where I wanted to go.

Made it, so worn out.
Do you know if the places around chiba are open on a sunday?
 

Not sure sorry. I went on a Thursday from memory.

Just a quick update, I made it back to Korea. 11 days in Japan really takes it out of ya. I'll do a write up in the next couple of weeks and get some photo's up for everyone. Thanks to every ones input here I had such an amazing time, without your help the trip wouldn't have been half as good. All the locals where very helpful and we even got to stay with a Japanese family for a few nights. I'm now trying to organise a little bit of work experience over there before I finish my degree, I met a girl here who's Father is an engineer at Denso, I expressed my interest and he wants me to send some more information and he'll see what he can do. Also I asked Crystal if they'd put me on for a month work experience, its not engineering but still a great excuse to get back to Japan. They said it depends, which is better than a no haha. I might even stop by on my way back to australia and have a chat. Only a couple of hundred more to do multi city stop over. My lack in Japanese language is the major concern or them I'm sure, either way I'm keen to start studying the language again.
Less than a couple of weeks left in seoul and back to the real world. 
I'll keep you all updated!

This is a bible!
I'm flying into Osaka, Kansai next month! from my motherland no doubt.
The Land of the Rising Sun is calling me...
can't wait :D

We went to Japan for a snowboarding holiday last year and all my missus did was take pictures of vending machines. Hopefully you find something more interesting to photograph. 

na/sdub 

We went to Japan for a snowboarding holiday last year and all my missus did was take pictures of vending machines. Hopefully you find something more interesting to photograph. 

LOL!
I bought a new decent camera for this trip so I'm sure I will :P
I was told I have "lots of courage" going there solo and not speaking Japanese...haha

You just reminded me I better get onto doing a write up on my experience, I wouldn't have had such a great time without everyones input here.
A lot of people are worried about going without knowing the language, including myself. But once you're there you'll find it all works out. Everyone is happy to meet you and help.
I picked up basic Japanese pretty quickly when I was there and that helped.  My most used word would have been sumimasen, haha, meaning excuse me and I'm sorry. 
How long will you be there for and do you plan to go to Tokyo?