Why does my car get unusually good gas mileage than normal?

It's a 98 Honda Civic. I do 2 hours of Combined city and highway driving for 5-6 days a week. I kinda have a heavy foot, the rims are 1" bigger than stock and the car is due for it's next tune up this coming Monday. The car is rated at 28mpg combined when it was shiny back in 1998, and when I calculated mine i got 32 mpg combined, my calculation isn't wrong either as i have an mpg calculator

The Honda Gas Elves come to your car every night in their tiny blue shirts and put a gallon of gas into your fuel tank. You've been chosen this year in their random act of helpfulness.

Maybe because your keeping track of your mpg and that's normal. They all get 30-45 mpg. Make sure nothing wrong with your gas gauge & stuff. If its all good then your doing something rite! Good job!

Hi as mentioned above it is a 'HONDA enough said basically better engineered than most american cars built more like an old british one to finer specifications.

The oversized rims and tires are throwing your speedometer and odometer off. Get the speed sensor recalibrated for the oversized tires, and your fuel mileage will miraculously return to "normal".

The published mileage is only meant to compare how one car might compare with another. It has absolutely nothing to do with what mileage a particular car will get. To answer your question it might be because you drive more highway miles and fewer city miles than they used to get the published combined mileage figure, or you drive at different speeds, or your city miles have fewer stops.

The size of the engine and you don't rev your engine like a idiotic kid

JetDoc has it right. Your rims are giving you a false mileage reading.

Because Honda, buddy. Because HONDA.

The 28 MPG may be the city and highway combined average.

Filling the tank to the top then writing down the real odometer mileage, driving the car till the low fuel light comes on, refilling the tank, dividing the fuel used at the pump into miles driven is more accurate.

Because you are in dreamland and the gas elves are making you delusional.

It sounds like your mpg calculator is brokened.

32 is not unusually high for a civic. I have a later 4-door version automatic with larger engine and routinely get 30 or better with a heavy foot. According to the webpage below your model year can get up to 44 on the highway.

By the way, the rim size is not necessarily throwing off your odometer. Overall tire diameter is the relevant measurement. Larger rims do not necessarily mean larger tire diameter. It depends on what tires you are running. Most likely you have a shorter sidewall tire than original.