Going to look at a 2007 Yaris 2DR manual Trans hatchback

[Cigar_Maverick]

Howdy all!
First post. Looking at retiring my 1995 Geo Metro. Has been a great car, but all good things must come to an end.

A dealer about an hr away has a 2007 Yaris for sale. Asking price is $4800.00. It has 106,000 miles on it. Regular title. Manual transmission. 2 Door. Hatchback.

What should I expect for an average MPG? With my 3cyl Metro (2 door hatch with manual trans) I get an average of 39-42 MPG. Most (85%) is 60 MPH highway driving.

Is there anything I should be weary of when I go look at it a second time? I'm taking a buddy of mine who is a mechanic.

When I test drove it the first time, I took it to an O'reillys and had them hook up the diagnostic as the "Check Engine" light was on. Said it was an O2 sensor. I'm fairly good with a wrench, it that an easy enough job?

The car does need new tires and has the normal wear on it. Was thinking of offering $4000 cash if it checks out. Thoughts?

Thanks!
Russ