The BAR was designed and engineered by Adrian Reynard, a brilliant designer who never had a failure in any class (and it was most of them) of car until the over ambitious British American Racing team was born.
The chassis was pretty average but the weak point was (surprise!) the engine, expecting a decent package from Renault but getting the 'Mechacrome' lump instead as Renault had decided that they were getting out of the game for the time being.
Williams ended up with the same package and had a miserable season.
BAT Reynard had their usual FIA bureaucracy troubles as well, Dave Richards (of Subaru WRC fame) wanted to run one car in Lucky Strike colors and the second in Triple8 blue and gold, you can't do that he was told, so the awful two 'half car' livery resulted.
Arguably the worst paint job on any race car ever at the time, I really felt for the crew who wore the same design on their uniforms for a complete season!
I think Benetton had been sold on to Renault and they were running a very special Renault 120 degree V10 which was
not for outsiders, so Mechacrome became the supply and maintenance engineers for the 'old' Renault lump.
Don't quote me, it's late and I'm a bit knackered!
The only comparison that can be drawn between BAR Honda (as they became) and McLaren Honda is obviously the engines.
The V8 wasn't a bad design, it was hobbled by the ridiculous regulations that 'standardised' engines to the point where the Honda engineers ability to innovate was stifled, rather like the present day where they can't get enough testing miles up find the best balance.
Honda floundered through the Honda/Honda period after they acquired BAR, mainly because they never were a success as a team, their strength lay as an engine supplier and developer.
The current McLaren is a first class chassis, no argument.
A little Honda history to consider:In late 1982 Honda tested with Spirit Racing, a minnow of a team, and in 1983 they formally entered F1 with Spirit (very short term) and gained practical on track experience, so much so that their 'new' partners debuted the Williams FW09 Honda in the South African GP where Keke brought it home in P5.
The FW09B Honda caused Williams plenty of aggro throughout 1984, despite Keke winning in Dallas. For 1985 the Williams FW10 and FW10B were finally of carbon fibre construction, with Mansell and Rosberg winning two Grands Prix apiece.
Honda became the dominant engine supplier from 1986 through to 1992.
Considering 1983 was very ordinary, 1984 less so, 1985 better and from 1986 they became
the force to beat, I'll bet real money the 2018 McLaren Honda will be at the pointy end of the grid.
What was the question again?