Mercedes-Benz claims that the new E-Class can return a very generous 4.3 l/100km. I wanted to see just how close to that figure I could get - without driving consistently below the limit. I set myself rules. Firstly, if I could safely maintain the speed limit on any road, I had to. I also set myself a target of covering over 800 kilometres. 130 of those kilometres were done in cities - travelling from one end of Dublin to the other on my daily commute and then a spin through Belfast and Newry. My next rule was to ensure that I covered motorways, dual carriageways and country roads - that was easily achieved, I took a spin to Rossnowlagh in Donegal and back. Read our full review here.