Why are we so attracted to fastback hardtops on roadsters?

Colin
By Colin Wood
Aug 21, 2021 | Miata, Boxster, S2000, hardtop

Photograph Courtesy Mazda

A fastback hardtop often adds a certain je ne sais quoi to a roadster, whether it's a Honda S2000, a Mazda Miata or even a Porsche Boxster,

How do you feel about adding a fastback hardtop to a drop-top sports car? Does it offer a worthwhile aerodynamic improvement, or does it defeat the whole purpose of getting a roadster?

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wheelsmithy (Joe-with-an-L)
wheelsmithy (Joe-with-an-L) GRM+ Memberand PowerDork
8/19/21 12:19 p.m.

Because Awesome.

 

Driven5
Driven5 UltraDork
8/19/21 12:25 p.m.

It defeats the purpose of a roadster, but makes for a great sports car.

David S. Wallens
David S. Wallens Editorial Director
8/19/21 12:32 p.m.

How about the Zeintec hardtop for the early Boxster? I shot this back in '07.

californiamilleghia
californiamilleghia SuperDork
8/19/21 12:55 p.m.

there were some cool Fiat 850 spyder fastback hardtops in the early 70s

Ian F (Forum Supporter)
Ian F (Forum Supporter) MegaDork
8/19/21 1:01 p.m.

Beats me... 

ShinnyGroove (Forum Supporter)
ShinnyGroove (Forum Supporter) HalfDork
8/19/21 1:10 p.m.

Sigh.  If they had put that NB coupe in the OP into production, it would probably be the most desirable car that Mazda has ever made.  For me anyway.  It's just beautiful, like a smaller FD.

 

Anyway- a lot of people like small lightweight cars, but don't like convertibles.  They're not great for motorsports, have poor aerodynamics, are noisy, and are only fun to drive with the top down a few months a year in most places where people actually live.

msterbeau
msterbeau New Reader
8/19/21 1:17 p.m.

Aerodynamically and structurally a way better deal.  

j_tso
j_tso GRM+ Memberand Reader
8/19/21 1:35 p.m.

 

ShinnyGroove (Forum Supporter) said:

Anyway- a lot of people like small lightweight cars, but don't like convertibles.  They're not great for motorsports, have poor aerodynamics, are noisy, and are only fun to drive with the top down a few months a year in most places where people actually live.

And if you don't have a garage the top has to stay up when parked which soon becomes a raggedy top.

bmw88rider
bmw88rider GRM+ Memberand UltraDork
8/19/21 3:22 p.m.
ShinnyGroove (Forum Supporter) said:

Sigh.  If they had put that NB coupe in the OP into production, it would probably be the most desirable car that Mazda has ever made.  For me anyway.  It's just beautiful, like a smaller FD.

They did just not in the US. 

https://www.motortrend.com/vehicle-genres/mazda-mx-5-miata-coupe-production-jdm-photos/

They are very rare and japan only but they do exist. 

Brett_Murphy (Agent of Chaos)
Brett_Murphy (Agent of Chaos) GRM+ Memberand MegaDork
8/19/21 3:53 p.m.

Right? And Mazda had to put out the dang ND RF instead of an actual coupe. 

frenchyd
frenchyd UltimaDork
8/19/21 3:53 p.m.
msterbeau said:

Aerodynamically and structurally a way better deal.  

Maybe not?    Aero wise a full windshield pushes a lot more air  than a speedster type convertible with a cut down  windshield or driver only windshield. 
   Now granted you only see those on race cars often with a tonneau cover over the passenger side. 
    I'm willing to bet such an arrangement push's at least 30% less air. 

NOHOME
NOHOME MegaDork
8/19/21 3:56 p.m.

Because the discontinuity of the lines in a convertible offends the primordial eye.

dean1484
dean1484 GRM+ Memberand MegaDork
8/19/21 4:03 p.m.

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Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/19/21 4:09 p.m.
Brett_Murphy (Agent of Chaos) said:

Right? And Mazda had to put out the dang ND RF instead of an actual coupe. 

We offer an RF coupe conversion kit.

All of my Miatas have permanently installed hardtops, my ND will be an RF and there's a good reason my MG is a GT instead of a ragtop. But there's a difference between a fastback hardtop and a coupe version of a roadster. The former tends to be awkward from a load space standpoint and is mostly for aero.

buzzboy
buzzboy Dork
8/19/21 4:36 p.m.

Didn't somebody make an NA/NB fastback with a drawer slide out? I remember reading about something like that years ago but I could have also dreamed it.

msterbeau
msterbeau New Reader
8/19/21 4:59 p.m.

In reply to frenchyd :

I'd like to see a comparison, in the wind tunnel, between the same car with a full windshield and well-shaped roofline and a SCCA prod car kind of aero screen and exposed roll cage.  What you gain in lower frontal area may be lost in a higher CD from the cage, driver and other random bits exposed to the air stream.  

Personally I feel better inside a full car with a roof.  Also, if we're taking about street cars, then the contest is easy because you probably still have a full windshield and the structural deficit doesn't get fixed by a cage.  

Aesthetically, I also prefer a fixed roof over a convertible but that's a personal choice and dependent on the specific car.  

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/19/21 5:05 p.m.

Tubes are really messy, aerodynamically speaking. I know my Seven picked up a lot of drag when the (fairly small) windshield was installed but even with the small frontal area it was draggy compared to a Miata.

80sFast
80sFast Reader
8/19/21 6:26 p.m.

I like fastbacks 

frenchyd
frenchyd UltimaDork
8/19/21 8:08 p.m.
msterbeau said:

In reply to frenchyd :

I'd like to see a comparison, in the wind tunnel, between the same car with a full windshield and well-shaped roofline and a SCCA prod car kind of aero screen and exposed roll cage.  What you gain in lower frontal area may be lost in a higher CD from the cage, driver and other random bits exposed to the air stream.  

Personally I feel better inside a full car with a roof.  Also, if we're taking about street cars, then the contest is easy because you probably still have a full windshield and the structural deficit doesn't get fixed by a cage.  

Aesthetically, I also prefer a fixed roof over a convertible but that's a personal choice and dependent on the specific car.  

Look at a 1955 Jaguar DType.  With only 250 horsepower it was doing over 170 mph at LeMans.  Then there are Indy cars as well as F1  with great big drag inducing open wheels.   
  I understand your preference to have a roof over your head. Not  only a real safety item,  but a psychological one as well. Most will agree with you.  

wspohn
wspohn SuperDork
8/19/21 8:39 p.m.

A Belgian garage, Coune, did a conversion on some MGBs that looked pretty good though I don't recall if it was removable.

 

My Solstice coupe has a fixed rear section and a removable top.  A private builder has made removable hard tops in that pattern for the convertible versions.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/19/21 9:21 p.m.

In reply to frenchyd :

F1 and Indy cars have open wheels because the rules say they have to. They'd be a lot faster if they were enclosed. 

If we're going back to the D type era (roughly speaking), let's talk about the Cobra Daytona Coupe. Created specifically because it had superior aero to the roadster, because the coupe 250 GTO was running away from the open topped Cobra.

jmc14
jmc14 HalfDork
8/19/21 9:30 p.m.

I really enjoy driving my Cheetah Roadster tribute.  Nothing like the open air driving experience for me. But,  I want a fast back hardtop version as well.  I've been working slowly on it.  I've built another frame.  And, have the Roadster body that I'm modifying.  LS engine, Tremec TKX 5speed, and C4 vette suspension.  A friend photoshopped a top on my Roadster body for me.  Still working out door ideas. The Cheetah had gull wing doors.  I'll probably go that route.  

 

frenchyd
frenchyd UltimaDork
8/19/21 9:45 p.m.

In reply to Keith Tanner :

I did say great big drag inducing wheels.  And the reason I mentioned the D type is if you look at my Black Jack you should understand.  

Tom1200
Tom1200 SuperDork
8/19/21 10:55 p.m.

In reply to ShinnyGroove (Forum Supporter) :

I like them to.

MadScientistMatt
MadScientistMatt UltimaDork
8/20/21 7:13 a.m.
Keith Tanner said:

In reply to frenchyd :

F1 and Indy cars have open wheels because the rules say they have to. They'd be a lot faster if they were enclosed. 

If we're going back to the D type era (roughly speaking), let's talk about the Cobra Daytona Coupe. Created specifically because it had superior aero to the roadster, because the coupe 250 GTO was running away from the open topped Cobra.

I was wondering how long it would take the thread to get to that. But since nobody has yet posted a picture of it:

 

Chris_V
Chris_V UberDork
8/20/21 7:40 a.m.

I'm the oddball here. I dislike those fastback rooflines on convertibles and I'll take the convertible version of a car 9 times out of 10 if it's available. I've had many convertibles in my life and prefer them over any other bodystyle. I love my MINI 2 seat Roadster in a large part because to me it looks the best of any MINI Cooper bodystyle. Top down OR up (though it's very rarely up), and it's so much more engaging on a twisty backroad.

Those Astons posted? Yes, they are pretty (and some of the best looking cars of the modern era), but the convertible version looks prettier to me AND you get the joy of top down driving. Were I to get an Aston (with the exception of the manual V12 Vantage, which is the 1 out of 10 mentioned above...), I'd get the Volante version every day and twice on Sundays. Same with the Jag XK8/XKR. I actually do not like the proportions of the coupe version at all. And same for the Miata in the OP. Dislike the proportions on that.

I'm not doing 190 down the Mulsanne so the very slight potential aerodynamic loss is absolutely unimportant to me.

This is:

madmrak351
madmrak351 New Reader
8/20/21 11:43 a.m.

For me it all started with the MGB GT. It made me wonder why the ratio of coupes to convertibles was not reversed! It looked to me like someone finished the jobl of designing the car. 50 years later I still feel the same. I will gladly take a frs/ brz/86 over a convertible Miata s2000 etc. 

Brett_Murphy (Agent of Chaos)
Brett_Murphy (Agent of Chaos) GRM+ Memberand MegaDork
8/20/21 12:06 p.m.
Keith Tanner said:
Brett_Murphy (Agent of Chaos) said:

Right? And Mazda had to put out the dang ND RF instead of an actual coupe. 

We offer an RF coupe conversion kit.

All of my Miatas have permanently installed hardtops, my ND will be an RF and there's a good reason my MG is a GT instead of a ragtop. But there's a difference between a fastback hardtop and a coupe version of a roadster. The former tends to be awkward from a load space standpoint and is mostly for aero.

Nah, it's because of this:

"The RF is a sexy little car, but its retractable top isn't structural. Because of this, many track organizations won't let them on track without some sort of supplemental protection."

I get *why* Mazda hasn't released it in a couple form in the USA, but I still wish they would.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/20/21 12:12 p.m.

If only someone had come up with that supplemental protection a few years ago :) You want an RF with track-legal roll protection? You can have one.

Aaron_King
Aaron_King PowerDork
8/20/21 1:47 p.m.

In reply to David S. Wallens :

I recognize that paddock. 

David S. Wallens
David S. Wallens Editorial Director
8/20/21 1:58 p.m.

Sort of related to this discussion, I saw a Porsche 968 convertible the other day. 

ebelements
ebelements Reader
8/20/21 3:01 p.m.

I think top down driving is the best driving, but it's hard to argue with the looks of the ND RF, F type coupe(first gen) and the S2000 with the Spoon hardtop.

David S. Wallens
David S. Wallens Editorial Director
8/20/21 4:23 p.m.

In reply to ebelements :

Everything you said makes sense: Love top-down driving, but that S2000 just looks so right. 

wheelsmithy (Joe-with-an-L)
wheelsmithy (Joe-with-an-L) GRM+ Memberand PowerDork
8/20/21 4:59 p.m.

Another:

 

Brett_Murphy (Agent of Chaos)
Brett_Murphy (Agent of Chaos) GRM+ Memberand MegaDork
8/20/21 11:00 p.m.
Keith Tanner said:

If only someone had come up with that supplemental protection a few years ago :) You want an RF with track-legal roll protection? You can have one.

I know, the quote is from the Flyin' Miata site. I'd just prefer to have it installed in the car from the factory as an actual hard top.

It's why I'm considering a BRZ over a Miata at the moment.

wspohn
wspohn SuperDork
8/21/21 11:21 a.m.

One of my old race cars was a fastback but not with a removable top.

Ditto for one of my old MG street cars (modified)

And of course:

 

buzzboy
buzzboy Dork
8/21/21 1:05 p.m.

To answer the original question: A convertible looks unfinished. A hardtop looks finished. A fastback looks like the car is in motion.

RichardSIA
RichardSIA Dork
8/22/21 1:14 p.m.

"We" do not.
Convertible = Sports car.
Fastback = GT car.
I have both and no problem differentiating them.

My Triumph GT6 has the difference right there on the body for the easily confused. wink
The spitfire does not need such as it's obviously not a GT.

I used to marvel at the guy who bought a new MGB roadster, had a hard top fitted, and then put a "Moon roof" into the hardtop.
The MGB-GT was available at the time.

mblommel
mblommel Dork
8/22/21 1:32 p.m.

In reply to RichardSIA :

So a Europa isnt a sportscar?

Chris_V
Chris_V UberDork
8/22/21 5:13 p.m.
mblommel said:

In reply to RichardSIA :

So a Europa isnt a sportscar?

Oh, let's not go down this rabbit hole too far. There's a reason the MGB GT got it's name when the hardtop was added. And the GT-6. And why 911s raced in GT classes. It's not an insult to call a car a GT when it is one.

RichardSIA
RichardSIA Dork
8/22/21 6:51 p.m.
mblommel said:

In reply to RichardSIA :

So a Europa isnt a sportscar?

By my personal definition, which used to be the common one?
An automobile designed to be more at home on the track than the street, with just enough street equipment to be legal.
No extraneous junk like cup holders or CD players.

So for the Europa lets see, negatives - roll-up (Power) windows, radio, fixed roof, ash tray.
Not much to hamper max performance.
Positives, - Extreme light weight, adequate power without being deadly, and superb handling. 
S1 first version with the bonded chassis and fixed windows was more a race car than street car, so rare fixed roof Sports Car.
Following versions got more civilized, higher mounted headlamps, separate chassis and slightly heavier to appease Fed. Gov. and insurance companies.
So S2 and TC clearly became GT's.
Nothing wrong with GT's, just not quite the same thing as a Sports Car.
There may be some rare overlap but most of what are being characterized as "Sports Cars" now are not.

 

mblommel
mblommel Dork
8/22/21 8:14 p.m.

In reply to Chris_V :

Why not? The ascertation was made that convertible = sportscar. I tend to disagree. And if roll up windows are too luxurious for a "real" sportscar then no sportscars have been made since the 1960s. You can define it in your mind however you like, but that doesn't mean it's true. The term GT was meant to refer to a Grand Tourer, a comfortable, fast, gentleman's car with sporting intentions that could be used for travel across the continent. Roll up windows and fixed roof don't necessarily get you there. Nobody is going to classify the tiny, uncomfortable, Europa S2 or TC as anything but a sportscar.

RichardSIA
RichardSIA Dork
8/22/21 9:56 p.m.

Why not? The ascertation was made that convertible = sportscar. I tend to disagree. And if roll up windows are too luxurious for a "real" sportscar then no sportscars have been made since the 1960s. 

Ah, you do understand!
Correct, no TRUE factory large scale production sportscars since the 60's.
Once Madison Avenue latched onto the term to sell two-seat T-Birds and pre-C4 'Vette's all hope of retaining the original meaning was lost.
A couple of generations later, and we end up with this discussion.

Convertible does not automatically mean sports car either, my Morris Minor Tourer is certainly NOT a sports car.
Even though it is more of one than so many modern versions, looking at YOU Camaro/Firebird - Mustang - Honda - Camry......

Even if we accept roll-up windows as acceptable to a real sports car the rest of the basic definition remains.
Nothing allowed that does not enhance the primary goal of beating the competition around the track.
By current loose definition my El Camino will be a sport car. wink
By my definition it will be a GT that can carry parts or provide a place to sleep comfortably.

ae86andkp61 (Forum Supporter)
ae86andkp61 (Forum Supporter) Dork
8/22/21 10:36 p.m.
RichardSIA said:
Nothing allowed that does not enhance the primary goal of beating the competition around the track.

Soooo...what do we do with these archaic definitions in 2021 when adding a roof, and all the added chassis  stiffness (not to mention the potential weight savings over a convertible) actually make the same car better for competition at the track?

I'm fairly certain that current Corvette and 911 coupes are better and faster than track work than the corresponding convertible counterparts...or am I missing something??? By the same logic, a Lotus Elise would be a sports car, but the Exige, which is faster, more track focused, and more Spartan is not?

RichardSIA
RichardSIA Dork
8/23/21 12:49 a.m.

I did not write the rules, just live by them.
As I recall the original rules came from an article I read dated from the thirties.
Fifties version was pretty much the same.
Nowadays?
Like I said, a couple of generations later we get this discussion.
Any car you want to label a Sports Car by your definition IS a Sports Car to you.
I may not agree with your definition, but so long as you are not forcing me to accept it, no problem.

David S. Wallens
David S. Wallens Editorial Director
8/24/21 12:48 p.m.
buzzboy said:

To answer the original question: A convertible looks unfinished. A hardtop looks finished. A fastback looks like the car is in motion.

Dang, that's good. 

Ian F (Forum Supporter)
Ian F (Forum Supporter) MegaDork
8/24/21 12:55 p.m.
RichardSIA said:

My Triumph GT6 has the difference right there on the body for the easily confused. wink
The spitfire does not need such as it's obviously not a GT.

A possible irony is my Spitfire with the hardtop fitted and the soft top removed is a better "GT" car than my GT6. The Spit has more usable cargo room.

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