W211 facelift – E280 Petrol vs E320 CDI (which one is smarter long-term?)

Hey guys,

I’m stuck between two W211 facelift options:

E280 petrol (M272, 231 hp) – I’d install LPG to keep running costs low.

E320 CDI (OM642, 224 hp) – V6 diesel, known for torque and economy.

Driving habits:

~70 km daily (gym, night drives, etc.).

Weekly city trip (80 km round trip).

Frequent 50+ km drives to see my girlfriend (highway + some mountain roads).

Around 24,000 km/year.

Fuel costs here:

Diesel ~2.43 BGN/L

LPG ~1.15 BGN/L

Thoughts so far:

E320 CDI → great torque + economy, but risks with DPF, EGR, swirl flaps, injectors, turbo.

E280 petrol → smoother and sounds nicer, LPG makes it cheaper to run, but higher base consumption and LPG system needs maintenance.

What I care about:

Reliability in the long run

Reasonable running/repair costs

Comfort (daily + mountain night drives)

Decent performance when I want it

👉 Question: Which is the smarter buy – E280 petrol (with LPG) or E320 CDI? What are the common issues I should expect with both engines and the W211 in general (facelift models)?