Someone please help me with this dilemma. My 2002 RX300 was used when purchased and is due for all the expensive maintenance - at least $1500 or more. Now with all the good car deals, would it be better to trade (this car isn’t paid for) or do the maintenance and keep driving. I am retired, single and live on a limited income. Help me make a smart decision.
You will be money far ahead by doing the required maintenance and keeping your car. I’m driving the '96 ES300 I bought new, and may keep it another couple of years. This assumes your RX300 is in good shape, of course.
With very few exception, it is almost always cheaper to keep what you have and do the maintenance and repairs as recommended or required. The car deals today are good, but they are really only good deals for someone who otherwise needs a new car. Any new car is going to still need maintenance.
$1,500 is what a couple of new car payments? You are going to need a lot more than that to make up the cost of car payments.
Cars are very poor investments. Keep what you have unless you really hate it, then don’t look for an excuse to buy a new one. If you can afford it, you have the right to buy a new one. No excuses needed. 
If you’re upside down (you owe more than the car is worth) then it’s nothing short of folly to get another car. You bought a premium car, expect to pay premium upkeep costs. Besides you try to unload the car right before some regular (yet pricey) maintence is due, the dealer or whoever you try to sell the car to will just deduct that amount from the trade in value or price of the car. You’re not going to come out a head either way. On short, just keep up doing the necessary maintence and continue driving the car for the foreseeable future.