Interesting that you should mention the 73 Pontiac Grand Am.
In the early seventies, my parent's had a 69 6.3 Benz and a new Grand Am two door coupe concurrently.
Compared to most other american cars, the Grand Am was a revalation. It had a relatively stiff suspension, fat radial tires on 15" wheels, anti sway bars, and a great rumble from the dual exhausts.
Certainly not the same level as the 6.3, which Mom still thinks of as her high water mark car, but both Mom and Dad enjoyed the Grand Am.
Quality and material were in two different worlds, as one should expect, given the price differences.
The Grand Am had a couple of neat features that I've never seen in a MB, namely seats that swiveled outboard, and inserts in the front seats that could be either cloth or vinyl, depending on how you flipped them.
Maintenance-wise, the Grand Am was a workhorse, the 6.3 was a thoroughbred, but by the time the Grand Am was 7 years old, it was a beat puppy. Paint had dulled, weatherstripping was shot, lots of creaks, clanks, and groans from the car. Doors clunked shut, and although huge, did not impart a feeling of confidence.... The Pontiac was eventually given to a friend of my Moms, and her sun ran it into a gas station pump.... But up until the day they gave it away, it still ran like a train, and still do a *****in' burnout. Still had the original exhaust on it, and it still had a great sound.
The 6.3 is still around, having gone through a period of ownership where my we and my siblings dumped ungodly amounts of money into it, before regaining sanity and sending off to family friend, who is a huge MB nut. Joe still has the car in Ohio today.
I can give a direct comparision between two 1971s I currently have in the fleet: First, a 250C coupe with a M130 six fitted with Weber carbs and coupled to a auto trans, floor shift. The black on black car had been restored in 1990, then driven as a daily car for 5 years. I bought it after it had sat for a few years, and resurrected it mechanically. Car now looks pretty nice from 10 feet, and is still very nice inside, doesn't leak water since it had all new seals in 1990, and has a NOS true dual exhaust setup with twin chrome tips. Second is a three owner Elduhrado convertible with less than 100k miles on it, and basically original. Boss Hogg edition, white with a red interior. This car really needs a steer horn hood ornament and a dixie horn......
The first thing that jumps out at me is the diffence in absolutely every control and action on the car. The 250C still has that same snich to the door when closing that it had new, the headlight swtch feels like it's turning on a power grid, Mb Tex still looks great and the ride and handling as just what you expect when driving a Benz. The Caddy on the other hand, shows much deterioration in almost every aspect. Window and top seals, gone. Plastic parts on the interior, going or gone bad. Dash, amazingly not cracked
. Switchgear does not insprie confidence when operated, in either function or perceived longevity. Even with new heavy duty shocks, the car wallows along the road, and the front end is still tight! One thing the ElDuh will do, is smoke the front tires when launched, if you can stand to see the gas gage vsibly drop....
It's absolutely amazing to me to see the difference in the way the MB has aged compared to the Caddy. Both cars not abused examples, and I'll concede that the 250C has had a bit more work done to it, but that was 17 years ago! The 250C is still a great daily driver, and my daughter uses it as such every day. The Caddy is a great Saturday afternoon cruise around for an hour car, but not nearly as satisfying as the Benz.
Ironically, the Caddy is worth 5-7 times the Benz, I guess bad taste never goes out of style.
Jim