Fuel Economy - 6.8!

We went to visit the inlaws over the holidays, they live about 300 km away, makes for a nice drive, not too far but far enough.  On the way down I wasn't paying too much attention to fuel economy but on the way back I stopped for gas before we left and reset the fuel economy gauge.  The first 150 km or so is on a highway with a 90 km/hr speed limit, I was on cruise control the entire way with only one car to pass at a steady 105 or so.  I figured I had made good mileage but when I checked at our stop as we joined the main Trans Canada route I was at 6.8 L / 100 km.  I was amazed it was so low and at that point I decided to try and make it under 7 for the entire trip.

I had three passengers (although two were kids), winter tires and a bit of baggage on board so I was especially impressed with my half way mileage..... it was pretty windy and the wind was behind us so that may have also helped a bit.  I figured in order to make it under 7 I would have to drive extra conservatively the rest of the way especially considering most of it is divided highway where most people drive 120-125.

I started the second half of our trip at 110, my passengers (most importantly my much better half) wasn't at all interested in going any slower than that.  So along we went on the second 150 km of our trip with people passing us left right and center but my average L / 100 km was holding steady at 6.8.  Normally I would never have stayed at 110, I even thought about cutting back to 105 just to make sure but I held steady at 110.  Everything was passing me, Mazda 5's, Dodge Caravans, Honda CRV's..... yes everything was passing me.... but I would not be dissuaded from my task.  It briefly crept up to 6.9 and I was getting worried but I figured the last part of our trip was mostly on the downgrade so I would be good, then sure enough it went back down to 6.8.

As I approached the end of our trip I was holding firm at 6.8, I stayed under 7 and never even had to drive excessively slow, if I went the actual speed limit I wonder how low it would have been?  Also I used cruise control the entire way which also saves quite a bit on fuel and is recommended for highway driving.  I would like to try going the speed limit just to see what the results would be, my baseline is now 6.8 (or 34.6 MPG).