Keep trying! It is definitely possible to achieve 29 mpg's on the highway. I did it at sea level on flat terrain in normal mode without much difficulty. The LC had 20 inch OEM wheels and a crossbar but otherwise unmodified.
Below is a summary of information that may be useful if trying to maximize fuel economy.
Background
First, It helps to understand the design philosophy as described by Toyota because the I-Force Max 2.4L hybrid is different than traditional combinations of twin turbos, superchargers, hybrids, or AWD EVs. It uses a standard inline four cylinder turbo as the ICE, mated to a standard 8 speed transmission (less gear searching vs a 10 speed), and with an electric motor (EM) sandwiched in between.
This combination has produced the highest power, highest torque, and highest fuel economy ever in this class of its vehicles (LC and Taco). Other than the electric system, it leverages standard, well proven, and readily available light truck components for the engine, transmission, drive train, suspension, and brakes. It also has the promise of extending the longevity of the vehicle because it has fewer moving parts, and reduces the load on the ICE, transmission, and braking systems over its useful life. Only time will tell.
It is important to understand this architecture because in order to maximize performance the driving technique is counter intuitive. For fuel economy, it should be operated as a very low revving four cylinder vehicle rarely going above 2K RPMs. To do this, the driver must focus on leveraging the electric engine and induce its use as much as possible. Some call this "pulse and glide". Others describe it as driving by RPM vs MPH. Either way, the objective is use the electric engine more and the ICE less.
Driving tactics
1. The electric motor can sustain speeds up to 15mph on its own. RPM is zero and electric sound hums.
2. The EM can solely maintain speeds up to 30mph on its own. Once at speed, RPM drops to zero and electric sound hums. Soft pedal the accelerator so the ICE never kicks in.
3. The EM can sustain highway cruising speeds up to 65 mph while keeping RPMs within the peak torque 1700 to 1800 range using the pulse and glide technique. This gives rapid power delivery and forces the EM to provide the boost rather than revving the ICE or spooling the turbo. RPMs remain constant yet you feel the boost/pulse of the EM to push faster.
4. Just a note. Although not moving, I have noticed the vehicle can run the AC and other systems for a relatively long period of time while parked before the ICE kicks in temporarily and then shuts of automatically. This saves quit a bit of gas compared to other vehicles that must sit there and idle the whole time.
When people complain that they are driving 75 mph and getting lower than expected MPG it suggests they are thinking about it backwards. For those who would complain that it is too much trouble to think about and just want to drive the vehicle, remember that this philosophy will keep you constantly in the optimal power band (about 1800 RPMS) and provide the most rapid power delivery. In sport mode, it is a total blast.
By understanding how this very clever and capable system was designed and re-training your driving instincts it is amazing what can be achieved for both fuel economy and driving performance. I fully expect someone with a little time and practice can break the 30 mpg barrier soon.
Good luck
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