There are ways to decrease tax impact if done correctly. 

If you are able to make your normal car payments on a monthly basis, I wouldn't be too concerned about paying it down unless it impacts your DTI to the point that you cannot get financing for investment properties. 

Paying off any types of loans won't impact the gain or tax you owe. 

And secondly, is there anyone here who had cashflow properties in the 2008-2009 recession that were greatly negatively impacted (like, was it harder to find renters or did you have to lower your rents, etc.?)

Account Closed, I don't think this is a good plan at all.Besides losing 20% of your income, there are a number of other disadvantages:You can't force appreciation with a 4-unit.You're at the mercy of the fickle and emotional residential market.Based on that market the property may be worth significantly less than as a 5-unit commercial, instantly losing you money and impacting your ability to get a new loan. 

Doing BRRRR doesn’t have its separate tax impact.

@Michael Peralta I would not advise you to invest your cash if one deal will impact you that much.

May seem trivial but I'm noticing that little things can make a big impact on day to day operations, especially for repetitive tasks.

Also interesting in this question, I wonder if anyone here has done any research on this program...How long has it been around, how reputibale it is, and mainly what are the impacts.

How the bill impacts an investor is really a function of their goals.