The car is indeed a problem - several actually. First off, the seat was pushed all the way back meaning it was last driven by someone taller than the person allegedly seen outside 37SR. So that person, whoever he was, didn’t drive her car there (this is partly why I think the sighting was in fact of Suzy’s boss during his later visit).
Secondly, the car’s arrival opposite 123SR can’t be accurately timed. There are sightings of the car at noon, yet SJL did not leave the office until 12.40. WJ’s sighting puts it there at about 12.50. BW’s sighting puts SJL in her car in the Fulham Palace Road at 2.30. A bloke looking like James Galway got into a cab around the corner from 123SR at about 3 and said he’d just seen a couple “having a right ruck”. Two BT workers working right next to where the car was seen did not notice anything all day, however, and left at 4pm. At 5pm the owner of the garage it was partly blocking noticed it. All we can say for sure, then, is that it was there by 5pm.
Third, if you were going to abduct her from SR, why not just do so right there, and abandon the car? Why create two places where witnesses could see what you are doing? If it was a planned abduction, and she knew you, why not just ambush her where she had parked near Sturgis, and leave her car there?
Fourth, was SJL in the car? The seat position says not, the passenger door was locked while the driver door was left open, and her purse was left in the door pocket. That says the car had only the driver in it, and it wasn’t her. But there were no unidentified fingerprints inside and it had not been wiped down. So the driver either wore gloves (in July?) or didn't need to avoid leaving his fingerprints because they were easily explained.
In this context, DV’s hypothesis makes some sense. If she went to the PoW and her car were found there, that places her at or near the pub, and the game’s up. So anyone who killed her there would have to move the car pronto. If you look at the map, where it was dumped was basically the first left off the first left after you cross the river. If you’re driving an unfamiliar car in an unfamiliar place, you might well dump it thus.