it's a 2.3 L 4. The car is listed on kayseronline.com, if you want to look at it.
I'm also looking at 07 and 08 Mazda3's, the more basic 5 speed model, that has power doors and windows.
Looked at the mazda 6 on line.Ran a warranty history for you car looks clean with no open recalls. This year and model has been problem free, if it were automatic trans then you might have concerns.As always have car checked to see if it has been in an accident or any unusual damage. You also asked about mazda 3 excellent cars in manual trans model, you cant go wrong there either.Hope this helps if you need more let me know