Near where I work is a Subaru garage next to a BP petrol station. I was travelling up a country lane from work and approaching the junction to an A road where I would turn left and towards the petrol station. As I approached the junction this black Subaru absolutely flew past (must have been 100mph+) and it was raining heavily at the time. I turned left into the road and saw him drive into the Subaru dealer. After I filled up I walked into the showroom and the plonker in question was sat behind a desk. There were other customers and sales staff in the showroom. I walked up to his desk and said "Is that a race track out there ? I didn't know the speed limit was 100mph and did you realise it was raining blah blah". He jumped up out of his seat and said "Look it's nowt to do with you I was test drving the car. Are you the Mercedes driver ? Anyway you were nowhere near the junction". I said "I don't care how far away I was. If that's the way you drive normally then you are putting people's lives at risk and I may be not so far away from the junction next time". He followed me out of the showroom and said several times "just get in your Mercedes". First point is I'm not a busybody but when idiots drive that that and I've got chance to say something then I will. This guy was driving like a lunatic. Secondly what has the make of car got anything to do with my comments ? Thirdly why can't people just hold their hands up sometimes and say "yeah mate I was going a bit daft there". Instead he ranted to me as if it's my fault ! People like this just make me sick. I rang Subaru and spoke to another person in there and asked him to pass a message to this sales person saying I will be in contact with Subaru head office. I was considering emailing him (as I've seen his details on the website) but not sure that may rebound on me. What would other people do ?