OK firstly the car outside the house:-
1.) In your previous arguments you have said this could be a maroon hatchback or possibly an orangey / red Fiesta or possibly a brown / rust coloured car depending on which of the other possible suspects you think it could have been. How do you know the police have found this exact car when it could have been any of these 3 cars above apparently?
2.) The car was spotted at 1:30am by the neighbour (Paul). It is not apparent as to how far away he was from the car, how close were the nearest street lights or what he could actually see in the dark early hours of the morning. You also say that the cars lights were off but in other statements the lights were on - which is it?
3.) The car was spotted at 1:30am however the pathologists report states that the murder occurred between the hours of 9pm and midnight. By the time the car was spotted the murder had already taken place.
4.) According to the "evidence" you raise about the possibility that the murder was committed by a "known violent burglar" you refer to the story of "M.R" - i.e. Michael Rawlinson. This guy apparently drove around in his sister's red/orange car. I will go through your "evidence":
* He was investigated after being suspected of a robbery 2 weeks before Hilda's murder. Fibres were found at the scene but were not matched to him. His sister had called the police anonymously to inform them that he had obtained a change of clothes from her the day after this robbery. He was never charged for this robbery despite his sister dropping him in it. You then go on to say that 3 days after Hilda's murder the sister sold the car (presumably to try and hide evidence?). As you can see by the first incident, the sister wasn't afraid of dropping her brother in trouble with the police so why was she now trying to help him by hiding evidence?
* Two days after Hilda's murder Michael was again implicated in another attack where he (and his missus) kicked a middle aged man in the head until they thought that they had killed him. You then make a big issue about another anonymous call made to the police by one of his friends where has was "agitated and nervous" and he said "he had done it this time". This anonymous call was also made 2 days after Hilda's murder - i.e. just after Michael had nearly kicked a man to death. The timing of the events indicates that he was most likely referring to the incident earlier that day where he thought he had kicked a man to do death. He was later charged and convicted of this crime so presumably he had left plenty of evidence at the scene.
Someone who thinks logically, provides a nice contrast to the real world.