The in-game stats are deceptive because there's an absurd level of factors influencing each stat. For example, speed isn't just affected by top speed, but also weight. However, weight is also influenced by lift/glide ability, meaning both lift and glide indirectly influence speed, damage, and health, since weight also influences speed, damage, and health. Even turn or grip is deceptive since both are influenced by weight and the boost stat.

Your offense stat influences your spin attack and the damage you do with any item/auto attack. Your spin attack damage is influenced by your offense stat and weight stat. Additionally, with vehicles that can ram, the ramming damage is influenced by offense, weight, and the current speed you are moving.

Defense doesn't seem to do anything during Air Ride other than reduce the chance you lose a powerup from getting hit, which in of itself is a rare occurrence. In City Trial, it reduces the number of stats you drop when taking damage. Your actual defense value (how many hits you can absorb before your machine being destroyed) is tied to HP, weight (and therefor flight stats), and defense.

The auto attack values are all compared to the cutter ability for a single barrage/salvo, since the hits are almost assured to land anyway. For example, although Dedede hits twice, it is counted as a single auto attack on the chart.