If you are not dependent upon one vehicle for transportation and you're willing to risk losing a vehicle in an accident, then whatever your states required minimum insurance coverage should be sufficient, so long as no one is injured.
That is I think a misleading statement. All of the various bits of car insurance fall into one of two categories: what you would have to pay to others for damage you did to them, and what the insurance company will pay you for losses suffered from damages caused by "others" (in quotes because the cause of the damage may not be another driver, for instance, if a boulder hits your car.) The state minimum usually pertains to the former. (I am not aware of a state that requires the latter form of coverage, but some might.) The amount of the former type of insurance which you need to buy has a lower bound set by the state, and an upper bound set by your net worth. That is, you cannot predict what sort of awful carnage you might accidentally cause, and you are insuring your assets so that if the worst happens it does not wipe you out financially. This isn't always done solely with car insurance, it is common to have an umbrella policy on top of that, which would also cover your homeowner's insurance.
So, back to the "I drive an old car" situation. Once the car is only worth a few thousand dollars, and you have enough to repair available in your savings, and free for this task if need be, it doesn't make sense to buy the latter form of coverage. The former form of coverage is the same - that is independent of the sort of car you are driving. If you do make a claim the insurance company is likely to jack up your overall rate, including on the other parts of your coverage, so it can easily cost you more in a few years of inflated payments than they paid out in repairs. Also, as the previous poster indicated, for a few thousand dollars of repairs it is much less hassle to just write a check. You can still sue, or threaten to sue, the other driver whether or not you are insured. You will be out of luck though if they are uninsured. (Or not, since driving that way is illegal and they may be willing to pay you something rather than being reported.) Finally, for a really old car pretty much any crash is going to "total" it. That usually means a salvage title, which will make the car harder to sell. It may be that if you fix it yourself that the salvage title can be avoided. This, I think, probably depends on the laws in your state.