If the shock absorbers of a vehicle's suspension are filled with magnetorheological fluid instead of a plain oil or gas, and the channels which allow the damping fluid to flow between the two chambers is surrounded with electromagnets, the viscosity of the fluid, and hence the critical frequency of the damper, can be varied depending on driver preference or the weight being carried by the vehicle - or it may be dynamically varied in order to provide stability control across vastly different road conditions. This is in effect a magnetorheological damper. For example, the MagneRide active suspension system permits the damping factor to be adjusted once every millisecond in response to conditions.  General Motors (in a partnership with Delphi Corporation) has developed this technology for automotive applications. It made its debut in both Cadillac (Seville STS build date on or after 1/15/2002 with RPO F55) as "Magneride" (or "MR") and Chevrolet passenger vehicles (All Corvettes made since 2003 with the F55 option code) as part of the driver selectable "Magnetic Selective Ride Control (MSRC)" system in model year 2003.  Other manufacturers have paid for the use of it in their own vehicles, for example Audi and Ferrari offer the MagneRide on various models.
General Motors and other automotive companies are seeking to develop a magnetorheological fluid based clutch system for push-button four wheel drive systems. This clutch system would use electromagnets to solidify the fluid which would lock the driveshaft into the drive train.
Porsche has introduced magnetorheological engine mounts in the 2010 Porsche GT3 and GT2.  At high engine revolutions, the magnetorheological engine mounts get stiffer to provide a more precise gearbox shifter feel by reducing the relative motion between the power train and chassis/body.
As of September 2007, Acura (Honda) has begun an advertising campaign highlighting its use of MR technology in passenger vehicles manufactured for the 2007 MDX model year.