Is your 3.625 gallons based on an actual fill-up or just an estimate based on reading 3/4 on your 14.5 gallon fuel tank? We can't rely on your fuel gauge, we need an actual fill-up.

I've seen 150 miles on the first 1/4 tank in my Yaris. 1/4 of my 11.1 gallon tank is 2.775 gallons. This would equate to 54 mpg! But, it's not accurate. The only way to get a reasonably accurate mpg assessment is from fill-up to fill-up.

Your 235 mile fill-up was also probably considerably better than 16.2 mpg. Unless, of course you ran it completely out of fuel before you filled up.

Accuracy matters. How many miles did you actually drive? How many gallons of fuel did you ACTUALLY use?