First, the luxury car segment (MB, BMW, Porsche, etc) customers are not the same as the segment buying and servicing econo-boxes. They will not plunk down wads of cash on the worlds best car, if it is serviced out of the standard building.
While generally true, pretty much all Mini stores are attached to BMW stores, and SMART stores (now defunct) to MB stores.
So SMART cars were being serviced next to an S Class.
Furthermore, in the case of MB, they also service Sprinter and Metris vans at the same facilities.
There was a much larger price gap btwn a SMART and an AMG S 65 ($235k) than there is btwn an Accent and the G90, or for that matter, btwn an A Class or Metris van (starting in the low $30k) and the AMG S 65.
That was the lesson of Acura: Honda customers willing to step up in price, wanted a higher level experience than what they experienced at the Honda deal. Hence, Lexus and
Infiniti are all in stand-alone buildings. It was a dealer requirement. Yes, dealers are independent owner-operators, but franchise agreements can stipulate location and facilities. And, have an exit clause to punch a dealer's ticket should they choose to not abide by the rules.
But all that hasn't exactly helped higher end sales for Acura and
Infiniti.
The RLX has been a complete sales disaster and
Infiniti had long abandoned the flagship segment and these days barely sell any in the midsize sedan segment w/ the Q70.
Having separate facilities are nice and all, but aren't a guarantee of sale success.
Product (meaning the vehicles themselves) are the biggest denominator.
2nd: starting a new marque is an expensive proposition, especially if there isn't enough service or parts (highest dealer margin) business.
It's a lot more expensive these days than it was during the late 1980's when the Japanese launched their lux brands.
An MB dealer is not going to stick a Toyota or other commuter car dealership under the MB (or BMW, or Porsche) roof. It would cheapen the cache of the MB brand and lose customers.
As pointed out above, many MB dealerships had an adjoining SMART dealerships (many times, the SMART showroom building was directly adjacent to the MB showroom).
A lot of large dealer groups have
auto malls - where numerous brands are situated in one large locale.
While they usually have separate buildings/showrooms, they often share 1 or more service buildings/service bays.
There one which has a Porsche dealership and a Kia dealership (among others); not sure if there are separate service facilities.
The offset is used cars, also highly profitable. Yes, the SUV is important a line extension. But, remember, Lexus, Acura and
Infiniti brands all started with two models. Acura has lost their way in product design but Lexus is kicking ass, taking no prisoners and customers from MB,
Cadillac and all of the other non-upper tier segment (Lambo, Ferrari, etc).
Again, significantly more expensive to build out a new dealership today and to keep it operating than it was 3 decades ago.
Wouldn't say Lexus is
kicking ass.
They've actually been
losing their higher-end customers (GS and LS) to the Germans and to Genesis.
They sold a whopping
335 of the GS and LS last month.
There's a reason why the GS is being discontinued and why the LS isn't making any $$ for Toyota.
In terms of what actually
sells - Lexus these days is not that diff. from Acura.
Unless dealers do create (and are required to create) a separate stand-alone building staffed with luxury car personnel, Genesis will be a very nice Hyundai.
For the more informed, Lexus increasingly is being seen as a very nice Toyota - due to their sales now being dominated by the UX, NX, RX and ES (Lexus counterparts to the C-HR, RAV-4, Highlander and Avalon).
The G70 has been in shoot-outs w/ the Germans (so has the
Stinger and
it's a Kia).
In pretty much every article about the GV80, it has been compared to the X5, GLE, Q7, along w/ the
Aviator.
The RX/RX-L does not get that treatment.
In fact, for articles/reviews of the
Telluride and
Palisade, many of them say
why get the RX-L, MDX, XT6, etc. when can get the top trim of the Telluride and Palisade?