I would doubt you will really see the difference in fuel cost from the 21 to the 40 size. The 40 will burn more fuel if you are flying at full throttle however you just don't need to be at full throttle setting unless you are climbing (like during a take off). I fly a Pizazz and fly for 15 minutes or more then land with more than half a tank of fuel most times. When it is less I normally have been doing a lot of knife edge circles which require a higher throttle setting. Learning throttle management from the beginning (using the left stick including the rudder) is a very good thing. Since you have experience with the cars it should be very easy to learn. Think of the rudder stick as the steering. Works exactly the same. I have a student with a 25 size Tigre Trainer. It is a ball to fly but is really a little pocket rocket and not the best plane to train on.

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