Smart Engine Longevity

The following is a very normal conversation you’ll read weekly on smart forums and FaceBook sites.

Person – How long does a smart engine last?
Me – Which type?, there are major differences
Person – It’s a 600cc fortwo/700cc fortwo
Me – Expect problems around 70,000 miles, that’s when you’ll need the engine reconditioned.

This is the point where people without a clue, different cars or single case scenarios start chiming in.

My car is on 150,000 miles with no problems (owns a 451).
My car is on 250,000 miles with no problems (owns a diesel).
My car died at 20,000 miles (MHD with a snapped belt but carried on driving).
My car is fine at 100,000 miles (owns a Brabus fortwo).
My 700 is OK and is at 90,000 miles (doesn’t understand they are lucky and that’s not the norm).
All smarts will last forever if you service them properly (wrong).
My smart stopped working at 60,000 miles (water logged Roadster with electrical, not engine issues).
The smart engine will go to 200K if you service it every X miles (also wrong).
My 600 is on 110K, bought it last year, no problem (Doesn’t realise the engine has already been reconditioned).

Average Engine Longevity Facts

Before you start claiming your 450 has done a return journey to the moon on the same engine, look up the word “average”. Yes, there are freak incidents of the Suprex engine not shitting directly into its pants at around 70,000 miles, but that is just not the norm. Your single case scenario does not distract from the 1000 cars that have died at the same mileage. You only know about your car. Experts know about lots of cars.

600cc Fortwo 450

Expect problems around 60,000 miles.
Failed piston rings, burnt valves.
Cracked turbo manifold.

700cc Fortwo 450

Expect problems around 70,000 miles.
Failed piston rings, burnt exhaust valves.
Cracked turbo manifold.

700cc Brabus Fortwo 450

Seem to be OK until about 130,000 miles.
Mainly burnt exhaust valves.
Engine has an oil cooler which seems to help.

800cc CDI 450

Usually last in excess of 250,000 miles.
Diesel engines have a tighter tolerance.
Engines have an oil cooler which seems to help.
Rust tends to kill these cars before engine failure.

1000cc Fortwo 451

Expect to see mileages exceeding 200,000 miles.
The engines are reliable Mitsubishi units.
Even the MHD engine is reliable if the belt doesn’t snap (unlikely over time).
Should I buy an MHD?

800cc CDI 45BHP 451

Usually last in excess of 250,000 miles.
Diesel engines have a tighter tolerance.
Engines have an oil cooler which seems to help.

800cc CDI 54BHP 451

Usually last in excess of 200,000 miles.
Diesel engines have a tighter tolerance.
Engines have an oil cooler which seems to help.

If your EGR cooler splits, you can over heat the engine.
This engine is prone to snapping the crankshaft (possible MB229.51 oil issue).

700cc Roadster 452

Usually fine up to 180,000 miles.
Engine have an oil cooler and possibly better pistons and exhaust valves.
Water ingress and electrical issues will normally kill a Roadster before the engine fails.

700cc Roadster Brabus 452

Usually fine up to 180,000 miles.
Engine have an oil cooler and possibly better pistons and exhaust valves.
Water ingress and electrical issues will normally kill a Roadster before the engine fails.

All Fortwo & Forfour 453

Insufficient data. They seem fairly good though.
People worry because they believe it’s a Renault engine, however, it’s designed by Nissan.

All Forfour 454

Expect mileage to easily exceed 200,000 miles due to a bullet proof Mitsubishi engine.
Rust and poor driving is more likely to kill this car than engine failure.

Engine Designer/Manufacturer

450 fortwo Petrol – Mercedes
450 fortwo Diesel – Mercedes
451 fortwo Petrol – Mitsubishi
451 fortwo Diesel – Mercedes
452 roadster Petrol – Mercedes
453 fortwo Petrol – Renault/Nissan
453 forfour Petrol – Renault/Nissan
454 forfour Petrol – Mitsubishi
454 forfour Diesel – Mercedes