First of all it has to be "different" and offer something that can be marketed. This is "mid drive" (6 wheel platform of Pride Mobility etc?) or "standing" capability or off road abilities etc.

This marketing rubbish causes a few major problems on its very own!  Its VERY difficult already to design a good balance of components, a good COMPROMISE of all the different parameters, in a good basic powerchair without trying to make it do these extra tricks as well!

These compromises are good Range & Speed. This requires big batteries in both cases... And size (width and length and seat height) so it is useful indoors too. All of these are conflicting design elements as explained below.


Plus weight: lighter is always better!  It helps performance, range, curb and ramp climbing, manual handling etc. But big batteries needed for range are also heavy.
So good ramp climbing and curb climbing capability needs yet bigger motors and bigger Amp control systems.  And one of the factors they are balancing here is also cost... The been counters interfere and make our powerchairs worse.

A smooth outdoor ride is essential. Our streets are torture without either good suspension or big soft smooth riding off road style balloon tyres. Both of which adds cost, but more importantly eats into the battery size problem. Big tyres require the space needed by batteries. And batteries are the single biggest problem/compromise on any powerchair. Bigger diameter and fatter wheels /.tyres and casters give a much better ride outdoors. But make the powerchair physically bigger / less capable indoors.

Fancy "rehab" style seating. Seat risers, tilt and recline, elevating legs and so on are all unbelievably badly designed in most cases and MUCH heavier than really needed. Often these options mean both a higher seat, AS WELL as smaller batteries since the seating mechanism needs this space. So fancy seating, standing mechanisms etc always make for a less capable overall powerchair unless designed with much care. And often you end up sat far too high for tables, vans etc. And it impedes stability. Tall things fall over easier. They also increase the discomfort over outdoor bumps as you are jerked from side to side more. This causes more pressure sore issues from shear forces.  So be careful what "options" you choose!

So these points above are the BASIC compromises that the powerchair manufacturer has to make. There are others. But this will give you an idea of what to look for when choosing a powerchair.