45bhp Or 54bhp 451 Diesel?

Should I Buy The 45bhp Or 54bhp Fortwo?

Probably, yeah.

I Meant Which One Should I Buy?

Yeah, I know. However, it’s a question that only you can answer.

OK, What Are The Options?

45bhp model – early 2009 to September 2009
54bhp model – October 2009 to October 2014

Euro Emissions Ratings

45bhp model – Euro 4
54bhp model – Euro 5

Neither of these can be taken into the London Ultra Low Emission Zone (ULEZ).

45bhp 451 CDI

There are 3 problems with this model.

It’s older than the 54bhp model,
It’s slower than the 54bhp model with a slightly different turbo setup,
They are generally the same price or more expensive than the 54bhp model.

The good thing about this model is they are far more reliable (although mine did die at 60,000 miles).
Expect in excess of 250,000 miles with the diesel engine.

The price over the other model is because the 54bhp version has a bad reputation for reliability.

54bhp 451 CDI

There are 6 problems with this model.

The EGR coolers eventually split internally and leak and drain all your coolant into the engine.
The turbo and DPF temperature sensors are prone to failing, causing safe mode.
The DPF pressure sensor is prone to failing, causing safe mode.
It’s slightly worse on fuel than the 45bhp model.
The DPF can get clogged up if you don’t drive it properly.
The car requires special MB229.51 oil which is a very poor lubricant.

The good thing about this model is they can be cheaper to buy and far easier to find for sale. The downsides are that they are unreliable, eat through sensors and a replacement DPF is about £2000.

Owning A 45bhp 451 CDI

Fill it with diesel and drive. Don’t worry about remaps, just leave it alone and it’ll be reliable. Do your normal monthly oil and coolant checks.

Owning A 54bhp 451 CDI

Fill it with diesel and primarily drive medium to long distances.
Don’t do regular short journeys as the car won’t get hot enough to clear the DPF.
Always have a spare few hundred pounds just in case one of the sensors fails.

Don’t buy a 54bhp 451 CDI unless you drive over 50mph for at least 10 minutes for 3 out of 5 of your journeys.

I Do A Lot Of Short Journeys

Don’t buy a diesel 451, not even the 45bhp version. Slow, stop/start traffic and short journeys just won’t bring you particularly good MPG. Go and buy a small petrol car like the 451 turbo. Don’t buy the non turbo MHD as that is the least reliable engined smart available.

If you drive the petrol 451 turbo carefully, you can get better MPG than the MHD anyway.
If you drive the petrol 451 turbo fast, it’s way more fun than the MHD and the diesel.

How Can I Tell The Difference?

If you are buying a 451 CDI just from sales photos, hopefully they show the engine. The 45bhp model has an angled EGR mixing body…

…but the 54bhp model has a straight throttle body with an angled mixing body behind it.

Alternatively, if you can get the VIN code for the car, look at the first 9 numbers and letters.

WME451300xxxxxxxx = 45bhp coupe
WME451400xxxxxxxx = 45bhp cabrio

WME451301xxxxxxxx = 54bhp coupe
WME451401xxxxxxxx = 54bhp cabrio

Euro Emissions

The 45bhp CDI is Euro 4.
The 54bhp CDI is Euro 5.