Buying new can work out if you catch it at the right time, like when dealers may run specials or unload inventory. My other truck I sold, I bought new in 03'. Was an 03' V8 Mountaineer with every option except for awd. Came out to about 40K, I got it for 34K, same dealer had a slightly used 03' V8 awd Mountaineer on the lot that was for sale at the time for 35K. Sure I could have haggled and maybe gotten 1K off or whatever on the use done, but they were offering a special on 03's as 04' inventory was comming in. My uncle did the same thing with his Harley F250, was cheaper buying it new then a slightly used one b/c of the discount Ford was offering at he time. So it negates really any depreciation if the pricing is similar to a used one of the same year.
In most cases buying used will be cheaper, but if you catch the market at the right time like when new inventory is comming in, you'll get a sick deal on a new vehicle. Plus if your financing, financing a new car is almost always going to have a better rate/terms then financing a used one. New, you'll know the car is taken care of since its yours, warrenty etc. I could careless since I mod everything, my other truck had ported heads, cam swap, tuner, headers, full exhaust with no cats etc while under warrenty. But my dealer is cool and still did work under warrenty, most would find every way to deny you servicing in that case regardless of what the Magnusen-Moss Act states.