All else being equal, cars with CVTs are usually more fuel efficient than with other types of transmissions.
Because they're tuned to perform in a manner that delivers the maximum fuel economy in order to drag up the fleet average, driver experience be damned.
What's wrong with the driver experience? Mine seems fine. It's certainly better than the automatic transmission in my old car due to smooth and instantaneous power delivery with no "dead spots" for shifting between gears.
I've read there's inertia when changing ratio in automated CVT though. Maybe it's an old issue.
There's very little inertia in the belt and pulleys, no more than other types of transmissions.
I think this generally happens for two reasons:
1) CVT transmissions can generally handle less torque, so they get lower-powered engines to compensate
2) Some CVT's function with preprogrammed "shift points" for people familiar with conventional transmissions to not feel weird, ruining the main benefit of a CVT
FWIW, they're claiming the whole system (motor operating at optimal state point + IVT gearbox) is more efficient than the usual whole system (motor operating far from optimal state point due to size and weight constraints + fixed ratio gearbox). Which is not immediately implausible.
Anecdotally, we ended up with a Nissan Altima with CVT, the first automatic I had driven for years. I loved the CVT with its smooth transitions between gears and no loss of power. When we got rid of our other vehicle with a standard transmission and picked up a non-CVT automatic, I was stunned by how sloppy it felt. I hadn't realized or remembered how "normal" automatic transmissions behaved and it was very jarring.
Would you mind elaborating on the problem you have with CVT cars?
Subaru?
I own a '16 Impreza and it really drags at low speeds. It's my only complaint with the car however, and it is better with higher octane fuel.
Unless you're getting premature ignition in your cylinders from compression (knock) the higher octane shouldn't matter.
If its a turbo (i assume not?) the car’s ECU will compensate for lower octane. Source: me when, half asleep, I accidentally half-filled my 03 WRX tank with 87.