Home » Engines Of Varying Displacement: 1981 Cadillac Seville vs 2006 Chrysler 300C

Engines Of Varying Displacement: 1981 Cadillac Seville vs 2006 Chrysler 300C

Sbsd 8 1 2023 2
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On today’s Shitbox Showdown, we’re taking a look at two luxury sedans with V8s that are capable of acting like much smaller engines. One was an unmitigated disaster, and the other, well, the jury’s still out on. But before we pop the hood on those, let’s see how yesterday’s lawn ornaments did:

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Huh. I am surprised, and I’m not sure I agree. The Rodeo would make a fine beater, if you could hop in and drive it away, even if it needed some work. But the idea of resurrecting a non-running early-90s SUV has about as much appeal to me as a day-old Big Mac. I’ll take the Newport, keep the patina, and drop in an engine from a newer Dodge truck.

We all know what we love about V8 engines: the sound, the smoothness, the rush of torque that pushes you back in the seat when you step on the go-pedal. And we all know what their worst attribute is: fuel consumption. But what if you could have a V8 that was only a V8 when it needed to be, and ran on fewer cylinders under light loads to save fuel? Sounds like the best of both worlds, right? Well, GM engineers thought so, twice, and the second time were joined by Chrysler. It’s rarely the case that the sequel is better than the original, but this is definitely one of those cases. But let’s give them both a fair shake, and see what you think.

1981 Cadillac Seville – $2,900

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Engine/drivetrain: 6.o liter overhead valve V8, three-speed automatic, FWD

Location: Bakersfield, CA

Odometer reading: 19,500 miles

Runs/drives? Starts, not drivable

Cadillac’s midsized Seville was completely redesigned for 1980, from an unremarkable four-door sedan based on a Chevy Nova to a bold, dramatic reimagining of a 1930s luxury car. Bill Mitchell’s design featured a “bustleback” trunk and a long hood meant to evoke Cadillac’s glory days of fifty years earlier. But I remember my grandpa giving its design a less flattering appraisal upon first seeing one: “Looks like someone ran over its ass with a steamroller.”

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Powering this bold new styling were bold new engines: Oldsmobile’s utterly miserable 350 cubic inch diesel V8, and for one year only, in 1981, this abject failure: the 368 cubic inch V8-6-4. Throttle body fuel injected and computer controlled, this engine could run on four, six, or all eight cylinders, depending on the throttle input. But the system worked too slowly to keep up with demands, and drivability was appalling. Most V8-6-4s were converted to run in V8 mode all the time, which could apparently be done by cutting one wire, but then you were left with a huge, thirsty V8 that still had no power to speak of. The gutless Buick V6, available as a credit option, might have actually made sense by comparison.

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This Seville, with fewer than 20,000 miles on the odometer, apparently has the cylinder-deactivation system intact. The seller says it starts and runs, but can’t be driven, but I wonder if it’s actually just fine (or as fine as these ever got) and they just don’t know what to expect of it. The common complaint of these was a lag when switching back to eight-cylinder operation, making the car sluggish and feel like it’s misfiring. Of course, there may be something more serious wrong with it.

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Wonky engine aside, the rest of it looks like you’d expect from a malaise-era Cadillac with almost no miles on it: clean, but sloppy-looking. Build quality was merely a suggestion in the early Reagan years, but that was hardly a problem unique to Cadillac. These bustlebacks were never my cup of tea, but I know they have their fans, and this one is about as clean as I’ve seen in a long time. You could bolt in any Buick-Olds-Pontiac-Cadillac bellhousing pattern V8, leave the “MPG Sentinel” in the dash as a conversation piece, and cruise around in… well, I guess you could call it style.

2006 Chrysler 300C – $4,000

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Engine/drivetrain: 5.7 liter overhead valve V8, five-speed automatic, RWD

Location: Lake Oswego, OR

Odometer reading: 161,000 miles

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Runs/drives? Just fine

This car, I’m a lot more familiar with. I drive a newer version of it every day, same color, in fact. Chrysler’s LX platform is arguably the best thing to come out of the ill-fated “merger of equals” with Daimler. A large, comfortable rear-wheel-drive sedan was just what the Mopar faithful needed to forget the “nothing but K-cars” era. And the fact that it has lasted for nineteen model years and will be sorely missed when it goes away only drives home the fact that this is one car that Chrysler, in its many guises, got right. The Hemi V8 is, of course, a big part of that success.

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This 5.7 liter version of the V8 with the famous name features its own cylinder-deactivation system. Chrysler skips the six-cylinder mode and goes straight from eight cylinders to four, deactivating cylinders 1, 4, 6, and 7 at steady speeds. Advances in computer technology have eliminated the lag, and the Chrysler system works by collapsing the hydraulic lifters instead of disconnecting rocker arms, making for a simpler mechanical system. It’s generally a reliable and durable system, but there are reports of failures, usually caused by neglecting oil changes or using the wrong viscosity oil, resulting in bent pushrods and wiped cam lobes. You can turn the system off by putting the transmission in “Sport” mode, but it reverts to normal when you turn off the ignition. A more permanent disabling involves replacing the camshaft, lifters, and some other things.

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This 300 runs great, and has had some recent service including a fluid change to its Mercedes-sourced five-speed automatic transmission. Everything works except the display screen on the infotainment system; fortunately there are buttons and knobs for everything, but setting radio stations might be a bit of a crapshoot.

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Otherwise, it looks like it’s in good condition, and a hell of a lot of car for four grand, actually. And the fact that this one is in such good shape after 161,000 miles makes me optimistic about the future of mine. These are a great way to enjoy a Hemi without the boy-racer stigma surrounding the Dodge Charger and Challenger.

V8 engines have been a cherished part of the automotive landscape for more than a century now, but they’ve never been the most thrifty option. It’s a bit irritating that, now towards the end of their run, the multiple-displacement method of making them more fuel efficient has actually started to work, but better late than never, I suppose. You can either take the museum-piece 1980s version try to make it work, or just go for the ready-made 2000s version. What’ll it be?

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(Image credits: Craigslist sellers)

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Black Peter
Black Peter
11 months ago

While I like the bustle back Caddies, I have more appreciation for the Soviet staff car look of the Chrysler. Put some sinister looking flags on the front fenders and now we’re talking

Mr. Canoehead
Mr. Canoehead
11 months ago

My BIL (who never does any maintenance on any vehicle) had one of these engines in his pickup. It survived 150k miles in his ownership. One time the oil light came on so he kept driving it for about a week before the dealer could take him. They found no oil on the dipstick, and they had to convince him to change the oil rather than just filling it back up. That’s amazing durability.

Ricki
Ricki
11 months ago

hahahahahahahahahahahahahaha

The 80s did more damage to Cadillac than they did to the USSR.

TriangleRAD
TriangleRAD
11 months ago

Definitely the 300. I’ve never driven one but I’ve driven a few Chargers and was always impressed. I even spent two weeks with a rented Charger R/T with the same variable-displacement 5.7. I put 1400 miles on it and enjoyed every one. It made wonderful noises when given any significant throttle input, went from 40 mph to 95 mph in the length of a slow-moving semi, and delivered 29 mpg cruising down I-85 in 4 cylinder mode. It was outstanding.

OrigamiSensei
OrigamiSensei
11 months ago

The Cadillac has no chance here. It’s the worst of malaise-era crap with no charm, and I say this as someone who has a weird fondness for that era and wants to do a bonkers Viper engine build on an ’81 Imperial. Even dropping an LS into the bustle-back Caddy wouldn’t make it fun or attractive.

On the other hand, for as much as we all love to trash on 21st Century Chrysler products I’ve always found the 300 to be a perfectly acceptable ride. It’s my go-to option for rentals when I can get them, as they have adequate power, adequate size, and they aren’t half-bad to drive. This one looks to be in good shape and reasonably priced for today’s market. Someone in need of decent transportation could do much, much worse.

JDE
JDE
11 months ago

I had this exact car, I sold it with 180K on it, it was running fine, the oil type is important, but it never did tick on me. But the Shifter plastic safety thing broke as they all do. still it never left me stranded. I would definitely take that over a carb’d 80’s GM anything to be honest. what a nightmare under the hood.

Brunsworks
Brunsworks
11 months ago

For a split second, I read this as “Engines of Varying Disappointment.”

JDE
JDE
11 months ago
Reply to  Brunsworks

the early Hemi like this, if properly taken care of as far oil type and so on, is not dissapointing, they run powerfully and smoothly for a very long time.

Mike B
Mike B
11 months ago

I’m a weirdo in that I actually like these Sevilles. My grandfather had one when I was a kid. It was a light metallic blue, a really nice color. Dark blue velour interior, so comfy. I miss interiors like that. His originally had the diesel, he had it swapped out for a gas engine, not sure which one. I’d imagine whatever small block had the BOP bolt pattern. 301, 307? Today, one with an LS would be fun.

Between these two cars though, I’d pick the 300 as it’s something that can actually be driven with the reasonable expectation of getting to AND from where you’re headed. IMO the exterior styling has aged well, though that interior was horrible even when new.

Last edited 11 months ago by Mike B
ColoradoFX4
ColoradoFX4
11 months ago

This is just an unfair comparison for the Cadillac. You’d have to double the price of the 300 for me to even consider the Seville. Now, if you’d managed to find a diesel Olds to put up against the Cadi, that would be a tougher (and more miserable) choice.

Cyko9
Cyko9
11 months ago

I wanted to play into the funky style of the Cadillac, but sometimes a poor choice is just that. The Chrysler is a pretty good option, and irresistible in comparison.

Hotdoughnutsnow
Hotdoughnutsnow
11 months ago

“I’m gonna force you to love Mopar, whether you like it or not!” – M.T.

Freelivin2713
Freelivin2713
11 months ago

Mopar or no car!

Tristan Hixon
Tristan Hixon
11 months ago

Honestly? I think I’d take the Caddy and swap out the computer for an ESP32/RP2040. The computer in something so old is absolutely dirt simple, so such a cheap part would be a significant upgrade – plus, with a couple of extra sensors, it could run much more effectively. I suspect the mechanical disconnect system itself might be what slows the system up, but depending on how it works, faster actuators might be able to be installed with a little custom work.

A custom exhaust (modern cat, actuated valve to swap between a larger diameter pipe in 8cyl and a narrower in 4cyl), electric fan and water pump, and better intake (again with an actuated valve) would, with the new custom fuel mapping, probably bring the old engine back into the fun zone.

Last edited 11 months ago by Tristan Hixon
JDE
JDE
11 months ago
Reply to  Tristan Hixon

the only correct answer for the caddy is to swap an LM7 5.3 with corresponding 2WD trans, but that is even more money on an already overpriced pile of 80’s junk.

Tristan Hixon
Tristan Hixon
11 months ago
Reply to  JDE

I don’t think the answer is about correctness or not – I just think it would be fun to try to make the old, weird engine work the way they intended it to by utilizing modern tech to fill the gaps.

Pneumatic Tool
Pneumatic Tool
11 months ago

I voted for the hemi with a heavy heart. My old man had an ’80 Seville with the despised diesel. Frankly it always ran pretty well for him. It also had the two tone gold/copper paint and a sunroof with deep pile carpeting. I drove it a couple times and it was such a different feeling than my Mustang…it had presence. Yeah, I know that I’m in the minority here when I state that I kind of like the bustleback in a weird way, but maybe it’s just because I used to pilot the old man’s caddy with one hand draped over the wheel…big pimpin’.

Bizness Comma Nunya
Bizness Comma Nunya
11 months ago

Chrysler 300, easily. If the Caddy was in a RWD DeVille or coupe then maybe, but these FWD Seville just never looked right to me and their transmissions weren’t nearly as durable as the previous OG Toronado based trasaxles that were very stout.

Although this is the last iteration of the real caddy V8, they were stout as shit and (frankly) one of the better V8 engine architectures to ever come out of detroit. They had displacement up to 8.2 liters… yet they didn’t weigh much more than a SBC. They had a dry intake valley, so no need to worry about coolant leaks there. I think that in the 1980’s GM should have considered a new home for this motor, maybe in trucks instead of the BBC.

To prove their stout-ness… the person who held (still holds?) the gas powered land speed record at 415mph had a cadillac V8 and it was still using the CAST crank and 2 bolt mains….might not still be a record though.

Shop-Teacher
Shop-Teacher
11 months ago

I straight up HATE these bustle back cars with a firey passion. Even as a kid, every time I laid my eyes upon one, I’d get angry. I say this as someone who likes a lot of malaise era stuff, but these … Just no. Hemi 300 all day, every day.

Bizness Comma Nunya
Bizness Comma Nunya
11 months ago
Reply to  Shop-Teacher

Couldn’t agree more, they just always looked wrong to me!

Stephen Walter Gossin
Stephen Walter Gossin
11 months ago

As the other Chrysler 300 owner here (other than Mark), this one is easy. Although, that Caddy could be wicked cool with a junkyard Northstar or LS swap.

Fun choices and thanks, Mark!

MikuhlBrian
MikuhlBrian
11 months ago

Another Chrysler 300 owner here. My first was a Magnum SRT8 that I put a 300C SRT8 front end on. Currently at 231K miles. Just acquired a 2023 300C with the 6.4L V8. Just shy of 3K now. Love those hemis.

Dsa Lkjh
Dsa Lkjh
11 months ago

I prefer displacement on demand the Citroen 2CV Sahara way: fit a reliable and sort-of-economical engine in your car, and then put a second one in the trunk.

I’m a huge fan of engineering to improve efficiency (and I’ve done enough of it to easily offset my personal lifetime carbon emissions), but it seems really stupid to start with a 5.7 litre V8. It’s the wrong starting point. Anyone who cares about MPG wouldn’t be buying the 5.7 anyway. Just embrace turbo-downsizing and boost a smaller, more efficient engine to get the performance you need. It won’t have the charm of a V8, but it won’t have all the inefficiency either.

Although the problem with any engine design for efficiency is that the driver won’t read the manual, follow the suggested shift points or put any effort at all in to learning how to drive properly. So we have people buying 2.0 turbos for increased MPG, and driving around on boost all the time complaining that it uses too much fuel. Then you calibrate an ECO mode for them and they turn it off.

In summary: no one cares enough about efficiency to change anything at all about how they use stuff, and they will bitch about it if they detect the slightest change when you try to help them.

Gen-O Bernardo
Gen-O Bernardo
11 months ago

my uncle bought a seville new back then. he swore up and down that if you “perform regular maintenance” gm engines are world class. engine dies @ 6k miles. he doubled down and bought a Cadillac brougham diesel(wtf). that went as expected. never bought another GM.

Mike B
Mike B
11 months ago
Reply to  Gen-O Bernardo

He wasn’t completely wrong. A 305/350/454 from that time would probably still be chugging along today, as well as anything with the Buick 3.8L (3800) v6. Unfortunately, he just picked the two worst engines they made in that era.

GreatFallsGreen
GreatFallsGreen
11 months ago

The Seville could be novel in that weirdo way like others said, but it almost seems like an unfair fight, the Chrysler is in pretty nice condition and a nice price, and I’m a sucker for glowing electroluminescent gauge dials.

Michael Beranek
Michael Beranek
11 months ago

No surprise here. For the Seville to win, it would need:

  1. The Olds 307
  2. To be way cleaner
  3. To be running
EmotionalSupportBMW
EmotionalSupportBMW
11 months ago

I’m a conasuer of automotive failures. You put an engine somewhere it doesn’t belong, or really anything bizarre. I’ll wait 22 years till it barely runs and try to turn it into something cool. I own a fake Miata Capri for the sake of Christ. But that Seville, much like Alamillo Bridge is a bridge too far. I have some standards, I won’t go to Burger King and I won’t save this thing. It needs to put out to pasture Leigh the old name of the Washington football team. Let’s not forget GMs failure, but dear god let’s not do that again.

I’ll be remembering GMs Carlos Correa level swing and a miss. In the second best Mercedes Benz ever built. Doing whatever people do in Lake Oswego.

IRegertNothing, Esq.
IRegertNothing, Esq.
11 months ago

The Caddy is a ripoff for nearly $3,000. It doesn’t drive, and even if it did drive you’d still have a garbage engine that will disappoint you more than a brother-in-law who says he only needs to couch surf until he gets another job… and then stays long enough to claim squatter’s rights.

This isn’t a fair fight. I’ll take the car that runs and is an aftermarket head unit away from being fully functional.

Stig's Cousin
Stig's Cousin
11 months ago

A Seville like this in good running condition would sell for ~$6,000. $2,900 is a fair price. It may be an easy fix, but if not, you still are paying far less than one in good running condition.

The price seems high compared to the price of the Chrysler, but no one is cross shopping these two vehicles. No one is buying the Caddy to use as a daily driver (I hope). While they appeal to a limited audience, there are people who want these as classic vehicles.

A. Barth
A. Barth
11 months ago

Chrysler, please.

It’s a hemi-powered sedan for $4000, so the bang-for-the-buck is definitely there. I was unsure why the seller mentioned “Been a great car but I got a truck and no longer need it.” but there is also a reference to a “tow bar” – aka hitch receiver – being installed, so maybe the truck does all the towing now.

One headlight is clear and perfect; the other headlight and the fog lights are cloudy and aged. That – coupled with the new tires only on the rear and the expired reg – makes me think that the seller is doing the bare minimum necessary to unload the car. Not a bad thing, necessarily, but there may be other deferred maintenance.

The Cadillac, OTOH… yeesh. No.

Taco Shackleford
Taco Shackleford
11 months ago

I’ll take the Seville for the gas cap hidden behind the license plate.

Shop-Teacher
Shop-Teacher
11 months ago

GM did that in just about every car for decades. But something else if that’s all you want!

Stig's Cousin
Stig's Cousin
11 months ago

I’ll take the Caddy. I haven’t driven a Seville, but I have previously owned ’84 and ’85 Eldorados which are similar. These cars are incredibly comfortable. The seats are as comfortable as an expensive recliner, there is a ton of interior room in both the front and back seats, and the ride is very smooth. They obviously aren’t great from a performance perspective, but these are supposed to be isolation luxury and not sport luxury. I miss isolation luxury. Sometimes it is nice to float over the road and not feel any part of it.

Obviously, I’m not thrilled this has the 4-6-8, but it would be adequate with the cylinder deactivation feature deactivated. And while I generally hate powertrain swaps, one of these with a better engine would make a very nice luxury car.

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