I went to MI and back in the past few days and with around 450 miles back and forth I thought I'd really try and drive 55 mph this time. Well let's say I did between 55 and 60 thanks to the newly discovered 'books on tape' which still make the trip go fast.
I expected a new personal record and indeed I got one and after filling up when I got home tonight I calculated just under 59 mpg (58.8). It still left me with a feeling that with a VX you should be able to get more at these speeds. I remember another VX owner saying that he had trouble getting any less than 60 mpg with his VX...
I bought my VX with 213 Km on i and haven't changed the o2 sensor since I am getting a very decent mpg out of it. Now I am wondering if I would need to change the o2 sensor to get through that magical 60 mpg barrier? Would it be worth the investment?
Your mileage doesn't seem very far off from what others on gassavers are getting if you look at the other VXs in the garage. A new oxygen sensor may help a little, but as far as it being "hard to get less than 60", that is unrealistic. If this was the case there would be many more people with 60+ MPG 90 day averages in the garage. Looks like many people are in the low to mid 50s for an average. It would take awhile to pay for the O2 sensor if saving money is your main object.
If you haven't seen it already, this site seems to have a good deal (only $195) on an O2 sensor for the VX: