From Halopedia, the Halo wiki
The Ford F-150 is a real-world car. The Sandcat was uniquely customized with a UNSC theme by 343 Industries; according to Kiki Wolfkill, the Sandcat exists in the Halo canon as well. Galpin Auto Sports added modifications such as Addictive Desert Designs’ Baja XTR off-road conversion kit, which includes custom FOX Racing shocks, Deaver leaf springs, a Currie full floater rear axle, ADD fenders, side steps, a chase rack and 17-inch wheels with off-road tires to go along with a full custom Halo body wrap.
The M552 designation is based off Ford's P552 internal codename for the 2015 F-150, which the Sandcat was made from.