I bought my jetta for the sole purpose of using fuel I had been discarding for years. I have to drain about 1/2 gallon each day. Not because the fuel is dirty, but because draining the fuel from the lowest part of the aircraft tanks prevents accumulaion of sediment and water and verifies that the last time the aircraft was fueled, the fuel was clean. Essentially, if taken every day, a crystal clean sample is ensured every day. Compare this to your car - I would be willing to bet that your car probably has a fair accumulation of rust. particulates, and water rolling around in the lowest part of your tank. Eventually it clogs your fuel filter and makes your car run a bit rough until you change it. We in aviation prefer that only clean fuel goes through our filters and that we change aircraft filters due to scheduled maintenance. Waiting for it to run rough is not our option.
That said, Jet A, does not have as many BTU's as #2 diesel, and performance will more closely match what can be expected when you switch to #1 diesel in the winter. Personally, I have a 45 mile each way commute so I still have to buy plenty of heavily taxed diesel at the pump. The ratios I use it in negate the need for additives for lubricity. Supplementing with waste jet A, for me, merely brings my cost per mile way down. Any stories about someones car turning into a performance rocket by fueling with Jet fuel are just stories, if anything, expect power and mileage to decrease slightly on Jet A.
As far as the taxes go, Aviation fuel is taxed even heavier than automotive fuel. Gotta keep the airports and FAA going. It's all Uncle Sam's money to me. I'll worry about it when the electric car guys start helping to maintain the roads, for now they roll for free, but then they also pay taxes on their electricity that go towards maintaining the electrical grid. It's all taxed, no matter what you do, the government gets their cut. My employer paid taxes at the point of sale, I'm just utilizing what they are throwing away, all the while saving them the time and expense of disposing of it in other ways.