I agree with every word about the BYD, in fact I just recently helped a family member buy one. But how would you pick the Austin 7 over the Model T as your example revolutionary car? Serious question, you're obviously knowledgeable if you mentioned that vehicle.
You can check the video on the early generation cars reviewed by the famous Top Gear team members [1].
Austin 7 and its derivatives (notably Dixi that kickstarted the highly successful BMW car business), dictated and popularized the modern car architecture, interfaces and controls stereotype as we know today. In order to drive old cars prior to Austin 7, we probably need a manual before we can drive them except the Cadillac Type 53 car, the original car that heavily inspired the Austin 7.
Austin 7 is the lightest car and cheapest proper car of its generation, and even by today's standard and inflation. As crazy as it sounds you can even drive it now in the UK road without any modification [2].
It become the template of modern cars, made popular in the UK, Germany and Japan, and then the rest of the world since these three countries are major manufacturers of modern cars.
The lighweight and low cost price of the baby Seagull (smallest BYD), is very similar to Baby Austin (popular name for Austin 7 in the UK) innovation criteria.
[1] Jeremy Clarkson and James May Find the First Car [video]:
https://news.ycombinator.com/item?id=46409075
[2] Everyone should try this! 1924 Austin Seven - no synchromesh, uncoupled brakes, in the rain! [video]:
https://youtu.be/HpwSKVJptKw