Any diesel car with four-wheel drive and off-road pretensions, no matter how trivial, that can return close to 50mpg on a touring run is one whose economy should be lauded.
Overall, we achieved 39.6mpg during extended testing of the 220 CDI SE 4Matic version, so a routine return of something in the mid-40s should be achievable for most owners.
Likewise, there’s decent news when it comes to residuals. The Mercedes sits among a group of premium compact SUVs but, with stronger resale values, it’s likely to cost no more to own than a volume-brand alternative.
Of any, the SE specification is probably the one to go for: it comes well equipped, with an automatic gearbox as standard. Avoid any unnecessary options that won't give you a return when you resell the car.
Don't automatically discount the petrol variants, though. It's worth taking the time to work out a provisional set of running costs for both petrol and diesel GLAs, based on your mileage, instead of just opting for the diesel by default.