Cpi SM 50 vs Piaggio NRG

The Piaggio NRG passes its MOT first time more often than the Cpi SM 50: 65.5% vs 52.8%, a 12.7-point lead.

MOT reliability, side by side

first-time pass rate, outright fail rate and tests analysed · 2005–2025

Metric	Cpi SM 50	Piaggio NRG
First-time pass rate	52.8%	65.5%
Outright fail rate	37.7%	27.4%
Vs comparable bikes (age & mileage adjusted)	-20.9 pts	-6.0 pts
Engine size	49cc	49cc
Rank among all models	#5366 of 5428	#4992 of 5428
Median miles at test	5,094	9,874
MOT tests analysed	741	40,458
Most common failure	lighting and signalling	lighting and signalling

First-time outcomes on normal tests, 2005–2025. "Most common failure" is the component group with the most recorded defects on failed tests. Read pass rates against test counts: a smaller sample is noisier. Source: DVSA anonymised MOT results.

"Vs comparable bikes" is the first-time pass rate minus the rate expected for each bike's own mix of age, mileage and test class, in percentage points: positive means better than comparable bikes. How this works.

What fails, side by side

share of each bike's MOT tests that failed on the component · lower is better

Component	Cpi SM 50	Piaggio NRG
Lights & signalling	26.7%	15.0%
Steering & suspension	25.1%	15.5%
Brakes	14.6%	10.2%
Structure & body	6.7%	2.5%
Drive system	8.5%	0.0%
Tyres & wheels	3.1%	4.7%
Fuel & exhaust	3.4%	3.8%

A test that fails on two components counts once in each. Component links go to the bikes most likely to fail on it.

Pass rate by test year

first-time MOT pass rate in each calendar year both bikes were tested

Test year	Cpi SM 50	Piaggio NRG
2010	47.7%	63.2%
2011	45.6%	63.9%
2012	58.7%	63.4%
2013	56.0%	64.1%
2014	53.8%	67.4%
2015	50.0%	68.8%
2016	45.5%	68.0%
2017	62.5%	72.0%

Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.

Pass rate by mileage

first-time MOT pass rate by miles on the clock at test

Mileage	Cpi SM 50	Piaggio NRG
0k-10k miles	56.3%	71.3%
10k-20k miles	42.7%	60.6%

Bands with fewer than 30 tests for either bike are left out.

Cpi SM 50 vs Piaggio NRG FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Cpi SM 50 or the Piaggio NRG?

The Piaggio NRG passes its MOT first time more often than the Cpi SM 50: 65.5% vs 52.8%, a 12.7-point lead. Adjusted for age, mileage and test class, the Piaggio NRG still comes out ahead: -20.9 points vs comparable bikes for the Cpi SM 50, -6.0 for the Piaggio NRG. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Cpi SM 50 fail its MOT on most?

Lights & signalling: 26.7% of Cpi SM 50 MOT tests failed on it, then steering & suspension (25.1%).

What does the Piaggio NRG fail its MOT on most?

Steering & suspension: 15.5% of Piaggio NRG MOT tests failed on it, then lights & signalling (15.0%).

CPI SM 50 52.8% pass · 741 tests PIAGGIO NRG 65.5% pass · 40.5k tests

See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.