Which used Mercedes A Class hatchback should I buy?
The best engine is the 1.6, which has useful extra power over the 1.4, making it a lot less hard work on the open road.
There's no point buying either of the more powerful petrol engines, the A190 or A210 - all they do is cost more and show up the limitations of the chassis. Of the two diesels, the A170 CDI is far better than the unrefined and sluggish A160 CDI, introduced in 2003. However, it's more expensive to buy than the petrol A160, so only makes financial sense if you do lots of miles, when the better fuel economy will help it pay for itself.
Like most Mercedes, the trim choice covers Classic, Elegance and Avantgarde, with Classic SE introduced in 2003. Pound for pound, Classic is the best bet, but you'll need to upgrade to Elegance to be sure of getting air-con.
It's also worth buying a long-wheelbase model, introduced in April 2001. They're only a few hundred pounds dearer, but much more spacious.