WI: Steam cars in the 18th century

I have just read about Ferdinand Verbiest, a European missionary and astronomer in China in the 17th century. Besides being the Emperor's head astronomer, among other things, he also experimented in steam.

Around 1672, he designed a small, steam-powered trolley as a toy for the Emperor. That toy was quite possibly the first ever self-propelled vehicle in human history.

There were additional experiments in the 18th century, but none of them really led to anything. My question is, what if after this proved that self-propelled vehicles were possible, serious development began? If more people began to take interest, could we have steam-powered cars capable of carrying people over certain distances by the late 18th century? And what would be some ways history would be changed?

I foresee development of better treatment for burn and scalding victims, much flatter roads, and less racing.

I'm sure your familiar with the Stanley Motor Carriage Co.?

It's unlikely to change much early because a) you would still need to work on building suitable steam engines for real applications which IOTL, with only slightly less incentive, took a long time and b) these steam cars would only be useful on very well built roads, which were rare. But if you had things come together right, steam gurneys could pull cargo on main roads in highly developed countries by the 1780s rather than IOTL's 1830s.

From there on, you are still likely to see a rise of steam-powered boats and some form of railway, because the economics make sense and the technology of powered vehicles isn't up to the challenge yet. But it is quite likely the competition won't be able to kill steam cars, which will have implications for road building (potentially more emphasis on macadamising or alternative metalling) and steam technology. And burn treatments, because steam isn't mature technology yet and someone will build boilers like Microsoft built early Windows.