Dad is interested in buying another diesel

[w123fanman]

My dad has recently came to me for help with a possible purchase in the near future: a safe, reliable, fuel efficient car for my mom to drive to work. She currently drives a 1996 Mercury Grand Marquis LS on a 45 minute commute from one side of Metro Atlanta to the other. This Mercury is a great vehicle but it has 170,000 miles on it and only gets about 21 mpg because of its immense size. So my dad talked with our mechanic (who works on our Sprinter, the non-running 240D, and the Mercury) and he said his favorite Mercedes after the W123 diesel was the W201, liking both the gasoline and the diesel variants. After I explained to my dad some of the basic stuff I learned about the 190D from this forum he looked around a bit and found the prices he was seeing on craigslist and ebay motors for 190D's were very reasonable. So this is the question posed: Does the 190D meet all of the requirements stated above (safe, reliable, efficient) and are there any other cars at this price range ($1000-$5000) that do those three things better? Also between the different variants of the 190D, what is that average fuel economy?