Cardio != Fat Burning
Try out like a 3-4mph walk at a 5-8% incline on a treadmill for about an hour. This will burn more calories and fat than running 6-7mph like a normal cardio routine.
How hard and often do you work your core? Also bodybuilders going for the V shape barely touch their obliques except for like side crunches from added definition. Building your obliques a decent amount will get rid of that V shape quickly.
"A pint of sweat, saves a gallon of blood." - General George Patton