The Hyundai U engine is a series of three or four-cylinder diesel engines made for automotive applications by the Hyundai Kia Automotive Group. The U series of engines includes the smallest automotive diesel engines produced by Hyundai.

1.1 L (D3FA)

The 1120 cc U diesel engine is a 3-cylinder version of the 1.5L U series unit and is made with cast iron block and aluminum cylinder head with chain driven DOHC with 4 valves per cylinder, Delphi common rail direct injection (CRDi), variable geometry turbocharger (VGT) and intake air swirl control. Bore and Stroke are 75x84.5 mm. It creates 71 - 75 PS at 4,000 rpm and 15.6 - 18.3 kgm of torque between 1,750 and 2,500 rpm. It is one of Hyundai's most efficient engines with a fuel consumption of 4.2 L/100 km, and emits 112 g/km of CO2. The engine also incorporates a 1½ engine order balance shaft mounted under the crankshaft driven by helical gears to manage engine vibration.

1.2 L (D3FB)

The 1186 cc U diesel engine utilizes three cylinders and is made with cast iron block and aluminum cylinder head with chain driven DOHC with 4 valves per cylinder. It produces 75 PS at 4,000 rpm and 19.4 kgm of torque between 1,750 and 2,250 rpm.

1.4 L (D4FC)

The 1396 cc U diesel engine utilizes four cylinders and is made with cast iron block and aluminum cylinder head with chain driven DOHC with 4 valves per cylinder, Bosch common rail direct injection (CRDi), fixed geometry turbocharger (FGT) and intake air swirl control. It is a reduced stroke version of the 1.5L U series with Bore and Stroke at 75x79 mm. It produces 90 PS at 4,000 rpm and 22.4 - 24.5 kgm of torque between 1,500 and 2,500 rpm.

1.5 L (D4FA)

The 1493 cc U diesel engine has four cylinders and is made with a cast iron block, aluminum cylinder head with chain driven DOHC (4 valves per cylinder), Bosch common rail direct injection (CRDi), variable geometry turbocharger (VGT) and intake air swirl control. Bore and stroke are 75x84.5 mm. It produces 89 hp and 159 lbft torque in the Hyundai Getz and 108 hp at 4,000 rpm and 174 lbft of torque at 2,000 rpm in the Kia Rio and higher spec Hyundai Getz models. Introduced in 2005 this engine replaced the 1.5L 3-cylinder D-engine common rail Diesel sold in the Hyundai Getz and Accent models which was notably less refined.

1.6 L (D4FB)

The 1582 cc U diesel engine (known as D4FB) from the Žilina Kia factory in Slovakia is a bored-out version of the 1493 cc U series engine, 77.2 mm versus 75 mm. In 2009, it was refined to the 1.6 U2 version, with a new displacement, developing 126 hp and 195 lbft of torque.

1.7 L (D4FD)

The 1685 cc U2 diesel engine (known as D4FD) was introduced at the 2010 Paris Motor Show. This engine features chain driven DOHC with 4 valves per cylinder, common rail direct injection (CRDi), variable geometry turbocharger (VGT). 1.7 CRDI