The Honda R engine is an inline-four engine launched in 2006 for the Honda Civic (non-Si). It is fuel injected, has an aluminum-alloy cylinder block and cylinder head, is a SOHC 16-valve design (four valves per cylinder) and utilizes Honda's i-VTEC system. The R series engine has a compression ratio of 10.5:1, features a "drive by wire" throttle system which is computer controlled to reduce pumping losses and create a smooth torque curve. The engine uses many advanced technologies to improve fuel economy and reduce friction. Piston rings are given an ion plating and weight is reduced with plastic and aluminum parts and variable length intake manifolds that maintain ram air at a wide RPM range. The engine also features piston cooling jets, previously available only on high performance engines, and in the ninth-generation 1.8L Civic (2012-2015) the pistons are treated with molybdenum disulfide applied in a polka-dot pattern. The automatic transmission model is rated at California Air Resources Board (CARB) ULEV-2 (Ultra Low Emissions Vehicle) with fuel economy 25 mpgus city, and 36 mpgus highway. It also uses the same computer (engine control unit) controlled distributorless coil-on-plug ignition as the Honda K-series engines. As of September 2019, the R series engines were only offered outside of Japan.

R16

R16A

R16B

R18

R18A1

R18A2

R18A6

R18Z1

R18Z4

R18Z6

R18Z9

R18ZF

R20

R20A1

R20A2

R20A3

R20A5

R20A6

R20A9

R20Z1

R20Z2/R20Z3

LF (R20-based hybrid engine)

LFA1 (i-VTEC + Sport Hybrid i-MMD)

This version includes i-MMD ("Intelligent Multi Mode Drive").

LFB1 (i-VTEC + Sport Hybrid i-MMD)

This version includes i-MMD ("Intelligent Multi Mode Drive").

LFB-13 (i-VTEC + Sport Hybrid i-MMD, e:PHEV)

This version includes i-MMD ("Intelligent Multi Mode Drive").

LFB-H4 (i-VTEC + Sport Hybrid i-MMD)

This version includes i-MMD ("Intelligent Multi Mode Drive").

LFC-H4