Back with the 4+1, and giving the missus a lift to work up the A19 at 6:30am, the first mile is up a sustained moderately steep hill. A Kia ProCeed GT (201 bhp/265 Nm) decided to have a go and did fine in 2nd, but fell back in 3rd and 4th to 80mph and I easily passed it from 50mph and put plenty of distance between us to 80. When he did catch up, I put my foot down in 6th and went straight up to 100, and it took him the best part of 1/3 a mile to catch up. As I started to slow down to take my turn-off to Killingworth, he eventually got past with the engine absolutely screaming - must have been 4th gear acceleration outdone by my 6th gear acceleration.
So a bit of a mad 4 miles of a 16 mile round trip, although we were the only 2 cars on the road. I drove normally for the latter 8 miles and still returned an indicated 47.6mpg, with an ambient temp of 2C (no ice around). If i'd been moderately saintly both ways, I might've been pushing 49/50mpg. Doesn't seem much of a penalty for having some fun.
Amazed how quiet and composed the GTD was sat at 100 in 6th, doing 2750rpm.