I haven't a source for you, but as I recall an account that at one stage Trevithick and colleagues developed a road going steam traction engine in the early 1800s and a local magnate Lord de Dunstanville expressed interest. Reportedly Trevithick and his men had drunk too deeply celebrating their success and crashed on the way to the demonstration. So, assuming this is true, if the driver had stayed sober we could possibly have had steam cars and lorries by the time Victoria took the throne never mind railways by the 1810s!