The way I understand Eco/Normal/Sport modes are just shifting point. Eco - shifts as early as possible. Sport - shifts as late as possible (more gas used, 'faster' car). Normal - something in between... So if you are doing steady 70 mph it should be no difference, RPM should be the same. Or am I wrong?
It's not just shift point (at least in regards to the past few versions of these features). You probably won't see a ton of difference between normal/eco unless you're doing a long distance cruise, but sport will guzzle gas. I'm not sure if the system is actually different for the 11th gen, but my past civics that had Eco and "S" modes operated as such:
Eco dulls throttle response to lessen the effects of micro inputs (normal movements in our foot on the peddle that we don't notice but effect the up and down of the rpms) to help hold a steadier cruising rpm. It also dulls the A/C to help save power/gas. It also (at least in terms of my last few civics) applies a dead spot around 2,000rpm to encourage you to allow the car to speed up at a slower pace (more input on the gas pushes past this). The car tries to keep the rpms as low as possible through shifting and throttle modulation.
Sport increases throttle response to small inputs and overall puts and holds the car in the meat of its powerband so even cruising you're doing 2500-3000 rpm (rather than the normal 1500-1700) so that any input forces instant torque response. This guzzles gas tho because of the higher rpm running rate. Sport mode also "enhances" the faux shift points of the CVT. The car keeps the rpms higher almost like you're constantly running in too low a gear.
Normal obviously fall in between these two. But I'm sure still leans closer to an Eco setting than a sport setting for mileage reasons, but without the throttle dulling or rpm dead spot at 2000. But still allowing the car to cruise in a lower rpm and not at 3000.
Fun Fact: In multiple 0-60 tests performed on the civics in variation iterations that had these modes. Eco and Normal netted the fastest 0-60 times while Sport usually netted the slowest. I think because Eco and Normal don't exaggerate the faux shift points the car just enters it's torque range and holds... the sport mode tries to mimic a stepped auto, and these faux shifts mean the car falls in and out of the torque band, slowing the car down. A dead stop 0-60 is best done in Eco or Normal mode... however if you're already rolling, sport mode will offer greater instant feedback, such as during passing.
