2015 Smart Forfour: common problems and MOT failures

What goes wrong more than usual on a 2015 Smart Forfour?

Parts flagged at MOT more often on the 2015 Smart Forfour than on all cars registered in 2015.

• Ball joint2.7× usual
  Smart Forfour

  8.2% All 2015 cars

  3%

  Failed outright at MOT: 5.7%, against 1.7% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

• Exhaust emissions (catalyst)8.6× usual
  Smart Forfour

  4.3% All 2015 cars

  0.5%

  Failed outright at MOT: 4.3%, against 0.5% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £175–£900 (catalytic converter) ClickMechanic

  At the viewing: Look for smoke when revving the warm engine and for engine or DPF warning lights.

• Brake lights2.9× usual
  Smart Forfour

  5.8% All 2015 cars

  2%

  Failed outright at MOT: 5.8%, against 1.6% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £10–£80 our estimate

  At the viewing: Ask a friend to check every light while you work the switches: indicators, brake lights, fog lights and reversing lights.

• Anti-roll bar link joints2.9× usual
  Smart Forfour

  3.2% All 2015 cars

  1.1%

  Failed outright at MOT: 1.2%, against 0.4% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

• Exhaust system1.7× usual
  Smart Forfour

  3.9% All 2015 cars

  2.3%

  Failed outright at MOT: 1.8%, against 0.6% of all 2015 cars. The rest were advisories or minor defects.

  Rough price £100–£500 (pipe or section) ClickMechanic

  At the viewing: Listen for blowing or rattling from underneath at idle, and look for black soot around joints.

Common 2015 Smart Forfour MOT failures and advisories

The share of 2015 Smart Forfour MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Tyres
  32% of testsRough price £70–£150

  At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

• Brakes
  21% of testsRough price £150–£350

  At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.

• Suspension
  20% of testsRough price £120–£400

  At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.

• Lights and electrics
  14% of testsRough price £10–£80

  At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

• Wipers, windscreen and mirrors
  9% of testsRough price £15–£250

  At the viewing: Check for chips in the driver's view, and test the wipers and washers.

• Exhaust and emissions
  6% of testsRough price £100–£1,200

  At the viewing: Look for black soot in the tailpipe, listen for blowing from the exhaust and check for engine or DPF warning lights.

Questions to ask the seller before buying a 2015 Smart Forfour

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

1. Any recent work on the ball joint? (Flagged at MOT 2.7× as often on the 2015 Smart Forfour as on other cars the same age.)
2. Any recent work on the exhaust emissions (catalyst)? (Flagged at MOT 8.6× as often on the 2015 Smart Forfour as on other cars the same age.)
3. Any recent work on the brake lights? (Flagged at MOT 2.9× as often on the 2015 Smart Forfour as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?