Compact direct drive in-wheel motors with integrated inverters, control and brakes offer a number of distinct advantages compared to conventional electric drive systems. The most obvious being that the drivetrain is now packaged within the wheel freeing up space elsewhere, in addition many driveline components and their associated losses are eliminated and the vehicle efficiency, response and handling can be improved. In new vehicle applications this allows complete freedom for designers to optimize the vehicle layout, have more usable space inside the vehicle body and enables revolutionary vehicle concepts (which will become more important as road space becomes scarce and taxation measures migrate towards vehicle size). In retrofit applications the compact package allows an electric drive to be added to any existing vehicle without requiring any significant disruption to the vehicle platform to keep integration costs down. This represents an opportunity for OEM's to hybridize their existing vehicle portfolio in order to address more stringent fleet-average emissions legislation.Protean has retrofitted its Protean Drive™ in-wheel motors to a variety of different vehicles in both pure EV and hybrid configurations and has collated its findings over three years of track and road testing. This paper will distil the practical experience gained from these vehicle programs and illustrate some of the challenges and solutions associated with in-wheel motor integration. In doing so the paper deals with many of the key vehicle level topics, such as the CAN interface, vehicle control strategy, and brake integration.