Both the Velocity 390 2010 and the Velocity 400 Xover 2008 are modified-V designs, both built in composite, so the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
On paper these two are close siblings in the size department - Velocity 390 2010 at 39,7 ft versus Velocity 400 Xover 2008 at 39,0 ft. Weight tells a clearer story for trailering families: the Velocity 390 2010 tips the scales at 8 000 lbs - 1 000 lbs more than the Velocity 400 Xover 2008 at 7 000 lbs. That difference is meaningful if you're working within a half-ton or three-quarter-ton truck's tow rating, especially once you factor in a motor, gear, and fuel.
The power gap is worth calling out. Rated to 700 hp, the Velocity 390 2010 has a 400-hp advantage over the Velocity 400 Xover 2008's 300-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Velocity 400 Xover 2008 carries 400 gallons versus 200 gallons in the Velocity 390 2010. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Velocity 390 2010 is rated for 12 passengers, while the Velocity 400 Xover 2008 caps at 11. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Velocity 390 2010 could be the deciding factor.
Bottom line: Choose the Velocity 390 2010 if your priority is putting more people on the water - it handles 12 passengers and at 39,7 ft it has the deck room to back that rating up comfortably. The Velocity 400 Xover 2008 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 11 that costs less to run day-to-day.