Our family has two (2) 1984 M-B 190D - four door sedans, each with a 72 bhp diesel engine, and five-speed manual transmission. These were purchased new and each has over 480,000 miles on them ... and they consistently get 46+ mpg ... and other than normal maintenance ... not one ounce of trouble ... ever!!!
Now to get M-B to sell their A-Class or B-Class in the US with diesel engines ... a another story.
I have a 300D. Doesn't get the mileage you're getting, but still respectable. We'll see after I run some Diesel Purge through it if it improves a bit.
The thing I don't like about the A-Class is it's front wheel drive. Somehow seems wrong to call it a M-B. But they do seem nice, anyhow.