Your reply vis-a-vis a Mercedes vs lifetime earnings seems to imply that you are willing to sell your integrity for some value x: $(Benz - Toyota) < x <= ~$2,000,000 (spread out over a lifetime). I'm a bit incredulous that your reply was basically that the only reason you would act ethically in my hypothetical situation was because you required a higher bribe.
This is a classic mentality of victimization. By focusing on the theoretical harm that been done to the extent of all other considerations, you can justify anything. It's a dangerous mentality that has resulted in many evils throughout history. Hell, this is the same justification ISIS originally used when recruiting Sunnis who were tired of corruption and discrimination at the hands of the Shia Iraqi government, only with the economic context replaced by a political one.
A more mature ethical position would recognize that in some environments, while evil has been done which harms or disadvantages you, the strategy of employing "any and all effort necessary to further one's interests" is likely what gave the advantage to those who have allegedly disadvantaged you. If you successfully follow through with this attitude you'll likely perpetuate a cycle.
If you are going to cheat, break rules, or whatever you should do so because those rules or prohibitions have little or no moral and social value in the context in which they exist. If GPA is just a meaningless filter enabling incompetent HR departments at BigCo to trim down their resume pile, then sure, game the system to your advantage. But don't draw the conclusion that you are morally entitled to do whatever it takes to promote your own interests. That path leads to psychopathy.