[5.7 V10]

I've owned GT4 for about two weeks and i've noticed the bhp figures are different when you're looking at the whole garage compared to when you directly click a car.

For example. My Zonda shows 1029bhp, but when i'm in a race it shows 970. Another thing that's bothering me is i'm losing bhp; i started with 1033; then i did the 90 lap endurance Laguna Seca race and dropped to 980. Then with an oil change and a car wash it went back up to 1033; now i notice it dropping by small numbers.

Is this normal or is my game defect????