We drive a 2001 Hyundai 4 cyl. and a Dodge Neon 4cyl. The Dodge has 127000 miles on it and it gets better milage than the Hyundai with 80,000 miles. Both in excess of 30 mpg.
I also drive a 1930 Ford 4 cyl. whch gets about 15 mpg. with a fraction of the horse power of the other two.
Just an example of the variables we encounter.