In the carjacking narrative (
http://www.boston.com/2013/04/25/bombcarjack/1BtfEbMP8X2D8wDmhkzKNO/story.html) :
- TT carjacks the Mercedes while DT follows in the green Honda (Danny just calls it an "older sedan")
- They drove from Fordham & Commonwealth circuitously through some suburbs, crossed the river and ultimately ended up in Watertown, where DT ditched the Honda on a side street.
(from the above linked article):
Directed to a quiet neighborhood in East Watertown, Danny pulled up as told on an unfamiliar side street. The sedan stopped behind him. A man approached -- the skinnier, floppy-haired Suspect No. 2 in the photos and videos released by investigators earlier that evening -- and Tamerlan got out, ordering Danny into the passenger seat, making it clear if he tried anything he would shoot him. For several minutes, the brothers transferred heavy objects from the smaller car into Dannys SUV. Luggage, Danny thought.
- So now the Honda is on a sidestreet in Watertown, and both brothers are in the carjacked Mercedes with some of their transferred explosives. They drive around some more. Then....
Doubling back, they returned to the Watertown neighborhood -- Fairfield Street, Danny saw on the sign this time -- and grabbed a few more things from the parked car, but nothing from the trunk.
I don't know if "Fairfield Street" was the sign he saw and memorized as they were in the neighborhood or if that's literally the street the car was parked on - I personally think he memorized the street sign they passed while coming from/to the Honda. Anyway, they are now transferring even more things from the Honda, which is still parked on a side street in Watertown.
Later, after Danny escaped, the brothers apparently went back to claim the Honda in Watertown (this makes sense: their victim had just escaped and would be able to ID them and ID the car - therefore they were probably going to transfer back to the anonymous Honda) ... and their travels back to the Honda led the police to follow them there (Danny's phone/GPS signal being easily tracked) and then began the shootout.
[from this article:
http://usnews.nbcnews.com/_news/201...atertown-shootout-after-boston-bombing?lite]:
....a green Honda that appears to be the same car that was parked on Laurel Street, in Watertown, during the 200-round shootout there.
So as far as I can read the narrative, they didn't have to "go back for" the Honda, since that was the place they parked it earlier. I think that the shootout actually happened when they went back to the Honda for the second time that night.