Business level Japanese in 4 years??

Just curious as to whether people think it's possible to achieve business level Japanese in 4 years WITHOUT formal education.. I will be studying Mechatronic Engineering for the next 4 years at University and aleo want to try and obtain business lefel Japanese in that time.. I am open to using both tutors and going to Japanese language groups to learn as well as home study..

Possible?

I think it's theoretically possible, but you would have to actually live in Japanese. No more English books, Internet, TV etc.

I learned most of my non-business Japanese in two years, and speak it at home with my wife and her family, and often at work, but I'm not 100% fluent since I spend my free time in English. I get a little tired speaking Japanese and thinking Japanese and simply want to speak my own language.

I studied some business Japanese for a bit, but Japanese friends would just say how they almost never use it, and it would feel so frustrating. I gave up after three months.

But you can do it if the drive is there.

I did it in about 3 years... maybe a little less.

It really depends on a few things primarily:
1) Your talent for languages (and more specifically Japanese)
2) How much time you can dedicate to study (I spent about 2 to 6 hours per day actually studying, and the rest was filled with casual use of the language through friends, drama, music, etc.)
3) How driven you are to make your goal happen (many people are obsessed for the first 6 months, but then their interest corrodes slowly and they forget why they ever wanted to study)
4) What methods you use for self-study (I'm fairly tech-savvy so I used ever possible resource I could utilize to make my study more efficient)

There is a myriad of trivial things that will play into your learning experience, but those are probably the biggest elements which had an impact upon my own results.

Well since your degree requires actual effort and not one of those useless liberal art degrees, it's going to be challenging to split your time between that and Japanese. You can certainly achieve some level of proficiency and in most cases, the natives will cut foreigners some slack.

Basically you need to study hard but above all try to use what you learnt practically by practicing speaking, reading, listening and writing. It really is practice makes perfect.

Unless you have some kind of phenomenal talent for languages, I think you would need to study/practice pretty much full-time to have a hope of achieving that. I don't think the odd spare hour each day after your main studies would be enough to get to that level.