I took delivery of a 2004 luxury sedan. 2004 is not "old" to folks like my boss who restores late 1950's early 1960's Pontiac muscle cars. But it's only a few years from being deemed an antique so to me it's old.
Unlike my grandmas 1966 Lincoln that did have A/C but no seat belts because at that point seat belts were an option, this one has "dual climate controls", heated seats, bright light sensing rear view mirror and a bunch of other cool stuff now considered normal in todays rolling appliances once called automobiles.
Research so far has revealed there are some common things that plague the Lexus/Toyota vehicles to this day. It always daunts me how a solenoid that gives trouble in a 1973 Bronco still plagues Fords to this day. And yet since Lexus used the same parts in some cases I know how to fix it. So when the dual climate control gets stuck on heater I know how to fix that because my 95 Ford Ranger and my 97 Honda Prelude had the same mechanical issue. It's either rust in the bicycle brake cable type cable that changes how warm or cold air enters the system or it's a plastic worm gear is broken. Now in the case of the Lexus it could be an electric sensor is dirty so it is blind to the temperature inside the car and thinks the cabin is warmer or colder than it really is.
The challenge is not what is wrong. The challenge is getting my bloated carcass up under the dashboard anymore. The whole thing boils down to whether or not the car starts, or runs without spilling fluids like crazy. If it reaches that point I'll just pass it on to the next dummy. I call it my latest money pit but with lessons learned from previous projects the pit should be fairly shallow (knocking on wood).
It's pretty satisfying to take on a project once begun by my oldest son.
I told a friend not long ago "it's gratifying to know your kids have better transportation than their parents".