you will find the 120-115km/h zone and above is pretty fuel thirsty, about 80-90km/h is the most economical, you would have been probably sitting around or maybe even above (considering you had a trailer) 2500RPM, when you are doing 80-90km/h, she tends to be around 1500RPM, it's pretty big difference, she seems to love that speed. I notice even having the car with 4 other blokes in it, the consumption goes up big time, so having a trailer attatched on the back, it wouldn't have helped.