Ertiga diesel have best power to weight ratio in segment so its not underpowered, yes it have turbo issue below 2k RPM, when u need power & have to go uphills just keep RPM above 2k & it goes smoothly.
View attachment 170393
Sirji numbers are always half the story and reaching a conclusion based on numbers isn't good. Else get the gear ratios, power and torque curves etc and calculate again the variation in net torque reaching the wheels in different gears at different speeds. That only can give us a clear picture of the performance one can expect out of the car with complete details of in net power and torque variation in each gear and then we can have the real power and torque to weight ratio variations. Till then, numbers are half the story said. After all the vehicle has a number of gears while these numbers just tell about the power and torque at your crank but not what we get at wheels and the numbers those really matter are the ones we get on wheels. I guess you will agree on this one.
Rest I wish some day you get a chance to stop in the middle of a hairpin at its inner edge, that time i'd love to see how you manage to keep the Ertiga above 2k.
In my life, the Innova never demanded me to pull handbrake while starting on steep inclines, just slot first gear and the grunt is ample to make it surge ahead giving you enough time to leave the brake and move your foot to accelerator, none else made me feel that way barring the Scorpio mHawk, especially the new one which just loves crushing the hills.
While driving an Ertiga, every uphill start needs assistance from handbrake even if there are 5 people on board. Its something like my Corolla is, making it surge ahead is tough and after that one can keep the pace, its just that it require a higher number of shifts.
I have taken my Ertiga to all over the Himalayas and I managed mine pretty easily. And not only once but many times have gone to Shimla, Narkanda,etc. Yes there is turbo lag so all one needs to do is drop a gear and done problem solved. More amount of gear shifts are required in mountains, I agree but not as such a problem to irritate the driver. So I do not get your case here.
Although I have answered everything above but sirji I have a question for you and I am seeking its answer. Since you have also driven on hilly terrain in an Ertiga, I hope you may have driven on some narrow roads too.
Now what you have to say about the times you are charging ahead in second gear or maybe third and suddenly you find that you have to slow down or even stop on a steep incline to give way to some heavy vehicle charging towards you in opposite direction? If you still get enough time to downshift then accept my hats off. Personally I always got the time to downshift only if o am stopped or the heavy vehicle has passed on the narrow patches. Why? Because I am unable to take left hand off the wheel because of twisties.
Such patches can be easily found on the way to gangotri, badrinath, kedarnath etc.