Smart 451 - ForTwo

A 451 Smart ForTwo Coupe

A 451 Smart ForTwo Cabrio

Introduced in 2007 as the replacement for the 450, the 451 series of Smart was more about making it a bit easier to live with than the 450, so it was a little longer, a little wider (making it a little bigger overall) but still undeniably a Smart.

  1. Engines
    1. Brabus
    2. Electric Drive
  2. Transmission
  3. Trim levels
  4. Typical issues
    1. Engine/Suspension
      1. Why avoid the MHD?
      2. So, what sort of 451 should I buy?
    2. Interior
    3. VIN identifcation


The 451 came with 61bhp, 71bhp and 84bhp petrol engines at launch (only the 84hp was turbocharged, the rest were naturally aspirated) with the same basic three trim levels as the 450. Around late 2008/9, the 61bhp was phased out and the MHD engine became the only variant of the 71bhp engine you could buy. The CDI engine from the 450 was carried over into the 451 at this point too originally in a 45bhp form and then changed to a 54bhp form later on with modifications to meet the Euro 5 specification.

A 451 Smart ForTwo Brabus


There was also a Brabus tuned variant of the 451, originally with 98bhp but was latterly available with 102bhp. Like the 450, it featured a Brabus specific bodykit, revised suspension, Brabus specific wheels and a different engine map.

A 451 Smart ForTwo ED Cabrio

Electric Drive

Although the 450 was available with electric drive, it wasn't available to private customers. This changed in 2013 as an electric drive 451 became available to the public in both coupé and cabriolet forms. It was capable of about 90 miles of range and 81mph from a 75bhp electric motor. This variant, unlike the rest of the 451 in Europe, came with a traditional automatic PRND gearstick that would be used in the American specification 451s and in the 453.


Oddly, all of the 451 models came with a 5-speed semi-automatic transmission (as compared to the 6 speed found in the 450 ForTwo/452 Roadster/454 ForFour).

Trim levels

The 451, like the 450, came with a core variety of trims along with a number of special trim levels.

Name Badge Year(s)
BoConcept 2013
Boxfresh None 2011
Brabus 2007 - 2015
Brabus Tailor Made ?
Brabus Xclusive ?
City Flame 2012
Edition 21 2013 - 2014
Electric Drive 2013-2017
Grandstyle 2014
Ice Shine 2012
Lightshine ?
Limited One 2008
Limited Two ?
Limited Three ?
Night Orange ?
Passion 2007 - 2015
Pulse 2007 - 2015
Pure None 2007 - 2015
Urbanstyle None 2010

Typical issues


  • MHD models have an engine design flaw. This involves the auxiliary belt in the engine and if it snaps (due to high tension or misalignment of the drive pulleys), the engine is liable to overheat due to coolant not being pumped around the engine. The simple line is avoid this engine if you can.
  • The CDI variant with 54bhp (from October 2009 according to Evilution.co.uk) has a DPF filter to comply with Euro 5 regulations. This has been known to be blocked up due to the wrong sort of oil (not conforming to MB 229.51 standard) being used when serviced and the exhaust will probably need replacing if this happens (an entire unit as the CAT is also bundled with the exhaust).
  • The anti-roll bar bushes on a 451 appear to be a weak spot and wear quickly. If the car is knocking over bumps, this is a good sign that this needs checking.

Why avoid the MHD?

The MHD (Micro Hybrid Drive) is essentially a start/stop system. The theory makes sense since the Smart is at heart a city car. However, the execution is bad.

The key element is that there is a belt connecting the crankshaft to the starter/alternator and then, fatally, the water pump. The belt is under a load of load and if not monitored, the belt snaps. This leads to the battery not being charged but, more importantly, the cooling system dies. To complicate matters, when the MHD was made the only non-turbo petrol engine available around 2009,
the water temperature gauge was removed from the instrument cluster, so you get very little warning of the danger.

Smart themselves have tried a multitude of fixes to resolve this but it is still happening, hence is why the MHD is best avoided.

So, what sort of 451 should I buy?

For a reliable 451, buy either non-MHD 61 or 71bhp Smart or a 45bhp CDI. For a fun 451, get the 84bhp or any Brabus model. If you travel long distances, either the 45 or 54bhp CDI is also an option, bearing in mind the advice above.


  • From around 2009, the LCD gauge changed, removing the water temperature gauge. If this is important to you, buy a pre-2009 451 or fit a 3rd party instrument gauge.

VIN identifcation

VIN Number prefix Model
451300, 451301 Fortwo Coupe CDI
451330, 451331, 451332 Fortwo Coupe
451333 Fortwo Coupe Brabus
451334, 451380 Fortwo Coupe MHD
451390, 451391 Fortwo Coupe EV
451392, 451492 Fortwo Cabrio EV Brabus
451400, 451401 Fortwo Cabrio CDI
451431, 451432 Fortwo Cabrio
451433 Fortwo Cabrio Brabus
451480 Fortwo Cabrio MHD
451490, 451490 Fortwo Cabrio EV