2014 C300 (W204) M276 Engine Tuning


Millbury MA
Mercedes C300 2014
Hey guys, I was wondering if anyone has any experience in tuning my car? I have done a good amount of research but everywhere I look there seems to be contradicting information. After speaking with a handful of salesmen from various tuning companies most say that an ECU tune will do little to nothing for the car. However, Kleemann has told me that my car is actually the exact same engine as the c350 of that same year, just de-tuned. They went on to tell me that their specific ECU tune would essentially override the de-tune and make a small tune up from there. They claim a 50HP jump bringing it from 255-305 for around $800.

I have searched long and hard for dynos and cant find concrete evidence.
I was in contact with Kleemann & the owner replied to me stating that he ensures it would be a significant upgrade in performance or he would issue me a full refund.

I am also interested in hearing about any other tunes or just interesting things about my car. I'm just learning the ropes of the car world so please bare with me and my limited knowledge.

Thank you!


Staff member
Deal, Kent UK
A3 1.4 TFSI 150 COD
Hello there and a very warm welcome to TorqueCars. It's not just about the extra 50hp peak, it will raise power through the whole rev range.

NASP engines generally only give around 10-15% more power when remapped but if an engine has been detuned you can effectively unlock that missing power.

The NASP DE35 M276 came with the following power outputs...

185 kW (251 PS;248 hp ) and 251 lbft (340 N⋅m) of torque
215 kW (292 PS; 288 hp) at 6400 rpm with 365 N⋅m (269 lb⋅ft) of torque at 3000–5100 rpm
225 kW (306 PS; 302 hp) at 6500 rpm with 370 N⋅m (273 lb⋅ft) of torque at 3500–5250 rpm.

So yes there is a lot of missing power in there ready to be released. The cost does seem quite high to me, compared with UK prices.

If the car goes back to Merc for a service there is always a chance they will reflash it to the factory settings.

It does sound like you are getting a risk free offer there. Get it in writing and book in for a dyno run (but don't ever expect top figures, most dyno runs are around 10% lower than people expect - the key is to compare a before and after).

Merc reduced the compression ratio by altering the bore and stroke to produce the DE30 and this worked well as a turbo setup and I've seen those engines hit 500bhp with the right mods.