The OM 654q in the Mercedes-Benz B 220 d is the first four-cylinder diesel engine to comply with the Euro 6d standard, which does not come into effect until 2020 for new models.
An expanded near-engine emission control system with an additional underfloor SCR catalyst makes this possible. (The “q” designates the presence of the extended exhaust aftertreatment with an additional underfloor SCR catalyst.) (Earlier post.)
Even in demanding driving situations and under challenging environmental conditions, the B-Class remains within the emission limits. This is achieved by additional selective catalytic reduction (SCR) with an ammonia slip catalyst (ASC) in the exhaust system of the B-Class.
This allows a more generous dose of the reduction agent AdBlue, as any surpluses can be reduced and converted in the SCR. These surpluses (ammonia slip) particularly occur during fast temperature changes in the exhaust tract, e.g. when moving from city traffic to the highway.
The OM 654q offers efficiency-enhancing technological highlights such as steel pistons with stepped bowls in an aluminium block. The cylinder liners are coated using the further-improved NANOSLIDE process.
With a cylinder spacing of just 90 mm instead of 94 mm, the new engine is more compact than its predecessor thus allowing the exhaust aftertreatment components to be installed directly on the engine, where the exhaust temperature is higher, making for more efficient aftertreatment.
Despite having a lower displacement than its predecessor, reduced to just under two liters, and weighing around 16% less, the new diesel powerplant in the B 220 d has an output of 140 kW (190 hp)—10 kW more than the previous engine, and delivers an NEDC combined consumption of 4.2 liters per 100 kilometers (56 mpg US).
Apart from the OM 654q engine from the two-liter diesel model series adapted for transverse installation, the B 220 d features the premiere of a dual clutch transmission with eight gears.