Hmmm so your car weighs more to begin with, and then you're carrying probably about 130kg extra weight on average if there are 3 people in your car including you....
Lets do some math!

Fiesta 1.25 -> 73bhp, 1040kg -> 70.1 (power to weight ratio)
323F 1.8 -> 115bhp, 1430kg -> 80
Or if you had 3 OTHER people in your car, totalling 4 people:
323F 1.8 -> 115bhp, 1500kg -> 76.6
What subwhoofers and stuff did you have in your car?

When you work it out, there isn't much in it

EDIT: Just to clarify, I'm using factory power figures, and factory weights (I'm sure the 1.8 BA weights about 1200kg empty), and a 99-02 reg Ford Fiesta

I haven't taken things like weight loss due to rust, fat people, weight of fuel or anything else into consideration
