Abstract: The present invention is directed towards a vehicle for off-road use with an improved frame, rear suspension, fuel tank, air intake, and four-stroke engine. Preferably, the vehicle has four wheels and a rider sits astride thereon. The frame has twin spars and is formed of aluminum. The frame further includes a removable engine frame. In one embodiment, one spar is used as an oil tank and the other spar is a cooling fluid reservoir. A swing arm pivotally connected to the frame and rotatably supports an axle assembly. The swing arm is connected to the frame by a rear shock that is disposed on the central plane of the vehicle. The frame supports a front body panel that includes an engine, air intake that is high and forward on the vehicle. The fuel tank is configured and dimensioned to be disposed beneath a seat, and has a rear portion with a T-shaped cross-section. The engine of the vehicle has and electronically controlled fuel injectors, and has a forward air intake and a rearward exhaust.