For 2008 the RXV 5.5 took lessons from Aprilia's Enduro World Championship programme.
| MODEL | APRILIA RXV 550I 2008 |
| Year | 2008 |
| Engine Type | Four-stroke, 77° V-twin, SOHC, titanium valves |
| Displacement / Capacity | 549 cc / 33.5 cu in |
| Bore X Stroke | 80 x 55 mm |
| Compression Ratio | 12.0:1 |
| Cooling System | Liquid cooled |
| Max Power | 52.2 kW / 70 hp @ 13000 rpm |
| Max Torque | 65.9 Nm / 48.6 lb-ft @ 10900 rpm |
| Ignition | Electronic |
| Induction | Electronic fuel injection with integrated engine management, 40 mm throttle body, two selectable maps |
| Start System | Electric |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | 5-speed |
| Clutch | Cable-operated wet multi-plate |
| Final Drive | Chain |
| CHASSIS SPECS | |
| Frame | Steel perimeter frame with aluminium alloy vertical members |
| Front Suspension | 45 mm upside-down fork, double adjustment |
| Rear Suspension | Box-section aluminium swingarm, hydraulic monoshock with compression and rebound adjustment |
| Front Brakes | Single 270 mm disc, 4-piston caliper |
| Rear Brakes | Single 240 mm disc, 2-piston caliper |
| DIMENSION SPECS | |
| Overall Length | 2222 mm / 87.5 in |
| Overall Width | 800 mm / 31.5 in |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | 1495 mm / 58.9 in |
| Ground Clearance | 396 mm / 15.6 in |
| Dry Weight | 129 kg / 284 lbs |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | 90/90-21 |
| Rear Tyre | 140/80-18 |
| FUEL SYSTEM | |
| Fuel Capacity | 7.8 Litres / 2.1 US gal |
| Fuel Consumption | — |
| Top Speed | — |
For 2008 the RXV 5.5 took lessons from Aprilia's Enduro World Championship programme. It gained a handlebar switch for two engine maps, a new air filter, a relocated choke and longer service intervals, along with a new tank, handlebar, lighter headlight, digital dash and revised suspension settings. Buyers could choose under-seat tailpipes or racing side silencers.
