I don't know the price difference in Canada for gas vs. diesel, but in the US, diesel is much more and wipes out the advantage of fuel mileage. Also, diesel engines now seem to require more service and repairs than gas. I'd choose gas. The gas engine had most of the earlier problems worked out by the 2009 model year. 2010 and newer are the safest and will have a more modern Command system. I wouldn't worry about 100k km. as mine now has 150k miles and still runs like new. Pay for any used car to have a full check up by an experienced German car mechanic. Either a different dealer or a good independent. Does CARFAX exist in Canada?
I don't drive much really heavy city traffic with lots of stop and go, but get almost 20mpg in mixed town and highway driving and 22 to 24 mpg on a long trip with fairly fast and sometimes aggressive driving.
Many thanks for the feedback. Diesel car prices don't seem to differ much from gas car prices for the same model year and condition, but I might be wrong. Nevertheless, I will consider Gas over diesel. Does this car have the M272 engine? This is the engine I have in my 2008 W211 E-Class, and I am very familiar with.
The 2010 car I see for sale is gas, with 100K Km (60Kmi) and the asking price is C$10,000 (~US$7000). That's what makes it look suspicious. Yes, Carfax exists in Canada. I will definitely use it.