Despite developing the exact same 333 hp and 480 Nm (354 lb ft) of torque as the M276 DELA 30 in the Mercedes-Benz E 400, this is not the same engine used on the E-Class.
Internally codenamed M276 DELA 35, the all-new V6 sports a 3.498 cc displacement compared with the 2996 cc of the M276 DELA 30 from the Mercedes-Benz E 400 and the recently-introduced SL 400 Roadster.
Since both the horsepower and the torque are identical between the two powerplants, one would inquire as to what exactly is the advantage of the larger one. Well, to answer that we have to look at another difference, which is brought by the much lower charging pressure of the 3.5-liter engine.
While the three-liter V6 has a rather high 1.8 bar (26.1 psi) charging pressure, the new 3.5-liter achieves the same power output with just 0.7 bar (10.2 psi) of charging pressure from the two turbochargers.
This results in the same power output but a slightly smaller fuel consumption, with the CLS 400 using just 10 liters of fuel per 100 km (23.5 mpg), while the E 400 has to make do with 10.4 liters per 100 km (22.6 mpg).
We don't have a clue yet if either the better fuel consumption figures or the more relaxed mode of operation is the main reason behind the existence of the all-new V6, but what is known for sure is that Mercedes-Benz didn't go to all the trouble to create a thorough press release for the engine - which is why we got all of the information above from the Germans from MB Passion.
On this tiny bombshell, we are now waiting to see if the upcoming C 450 Sport will use a modified variant of the three-liter or the 3.5-liter V6, but we will have to wait a few more months to find out.