Since I had the bike in for the 600 mile service the gas mileage (according to the onboard computer) is way down. I had around 46 mpg before and on trips with Andrea on her own bike I was around 48 to 49mpg. Today we went for a ride again and I had a hard time getting it to 43mpg.
I will monitor that for at least a tank or two but will also check with SJ BMW whether the service included anything that might affect gas mileage. And no, I wasn't riding faster, if anything I was slower and more careful with Andrea in the tow.