E-class W124 vs C-class W202, fuel consumption and technical data?

I am currently driving an old (1989) Audi and am considering to buy another car. I had a look at the local market (South Africa) and it
seems that there are quite a few of the early C-class and the old E-class (W124) available second hand.
Is there a web site somewhere, which has the fuel efficiency of the different versions and some technical data on these?
What are the big differences between the C-class and the older W124? Here, the C-class tends to be a bit more expensive, but not much.
What milage can I typically expect before getting problems on these cars?
Is there anything in particular one has to check carefully, when looking at one of them?
Thanks a lot for your help,
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.