Some cars are already very aerodynamic and are probably already pushing what is possible within the confines of seating 4 people and so on.

I’m sure there is more to do, but there are other constraints to consider if you are thinking of radical changes;

Pedestrian safety
Size of vehicles
Image/marketing
Luggage space
Headroom
Visibility of corners of the car

Manufacturers first priority is to make money, everything else is lower priority. Even your greenest most eco-conscious packaging free shampoo soap manufacturer… Unless I suppose it’s got a Philanthropic backer to sink cash into the business knowing it’s never going to be commercially viable.

Can’t fit shit in really aero cars!

Although, saying that. I have a Ford SMax, which I’ve always thought looked pretty aero* and you can fit shit loads of shit in it.

*It probably isn’t though….

Yep, as matt says, bigger gains to be had by fitting 50mph speed limiters to every vehicle.
Imagine what would happen to a political party who seriously suggested that?

Modern cars have quite a few things to make them more aerodynamic than 20 odd years ago. Some small things make a significant difference. Modern mirrors are usually tear drop shape, Vectra was one of the first, windscreen wipers now park further down in the scuttle below the windscreen when not in use, aerials don’t poke out of the front, windows are flush etc.
One of the biggest gains is smoothing out the underneath with a sump tray and sometimes exhausts are a bit recessed. This let’s the air flow smoothly under the car. Lowering the car isn’t really practical for most cars as they’d hit speed bumps. A guy at work had the eco version of the Skoda Citigo and that was lowered to create less drag but even though it was short could catch aggressive speed bumps and some lanes or tracks needed to be driven with one wheel on the grass in the middle.
Formula one cars have huge wings that create masses of downforce to hold the car on the track bit also create lots of drag so not a benefit for normal driving.

Some cars are already very aerodynamic and are probably already pushing what is possible within the confines of seating 4 people and so on.

This.

But I think it’s also interesting that these are a small minority of cars sold, and that SUVs account for such a large proportion when their aerodynamics are so poor for the space inside (and all the rest of it) that they offer. The majority of people, I think, don’t understand the point about how big a difference aerodynamics makes. But I think it’s also true that a lot of people don’t really care, or have not been educated to understand why they should care.

We can’t replace aerodynamics with slowing down, because we can (and should) slow down a more aerodynamic car too. And then the big box is relatively bad in just the same way as before. OK the numbers are different but until you get down to impractically low speeds the qualitative point still holds. It’s not either/or.

There’s probably not much appetite for things like this, which is probably the sort of thing you’re looking at for any significant improvement.

They are and some rather clever techniques used to make them so while trying to remain practical.

This might be related, but why do some electric cars have wheels that look like dustbin lids?

Drag coefficient (Cd) was a marketing thing on cars from late eighties and early nineties. I suppose it’s been trumped by more objective fuel economy and emissions stats.

The VW xl1 has a drag coefficient of 0.19 which is probably as aero as you can reasonably get. The shape would be massive if it had to hold 4 people and some luggage, so that’s probably part of the reason why

Whilst I don’t expect to see F1 style cars on the road, I would imagine there’s a huge amount we could do to improve the way modern cars are punching holes in the air to make it more efficient?

Most (I’d image all of them probably) road cars have got massively lower drag coefficients than F1 cars.

Unfortunately frontal area has gone up and wiped out most of those gains.

Aye: https://www.newscientist.com/article/dn4462-suvs-double-pedestrians-risk-of-death/

It’s terrible. SUVs are the worst thing that’s happened to recent motoring. The ‘seating position’ argument that most of the population hark on about is trash. They are jacked up hatchbacks. If you need a more upright, natural seating position you use an MPV because that has the same floor height but much higher roof, and higher seats vs floor as a result. Rather than the whole thing just being on stilts.

I have a Ford SMax, which I’ve always thought looked pretty aero*

It’s not though, it’s just nicely styled. Look at the depth of the front above and below the number plate, the open spoked alloy wheels, the blunt rear tailgate with just a nod to efficiency by sloping the roof at the back.

My van is completely flat at the back, no effort to smooth airflow at the rear as volume and load length sell vans. 20 years ago van sides all sloped in as they got taller, sometimes the roof width was narrower than the internal wheel arches. This reduced the frontal area, especially the high top above the windscreen. Vans are all square now, wide at the top and all that internal volume results in more wind resistance.

There is talk about making a length allowance for lorries so that they can be more aerodynamic without affecting load capacity. Imagine what you could do at the front and rear of a box truck if you had an extra 150cm to play with that could not be used for load space.

The people who used to buy hatchbacks now buy SUVs and that the problem, but they aren’t buying range rovers.

Just taking people around me:

Peugeot 208 replaced with Renault Capture
Renault Megane replced with Renault Capture
Renult Laguna replaced with renault Capture
Citroën C4 replaced with Citroën C5 Aircross

You used to drive a Golf and A3 IIRC Drac but now drive an SUV. Your SUV rpelaced hatches, it’s elctric and won’t be poisoning people but it’s definitely an SUV with its inherent ineffciencies.

Yes, less aerodynamic ones dubbed SUVs. Because the manufacturers are replacing the aero-efficient models in their ranges with SUVs. Citroen are typical:

https://www.citroen.fr/vehicules-neufs/types-de-vehicules/voitures-suv.html?_type=380&gclid=CjwKCAjwqIiFBhAHEiwANg9szjs12WNRodAucs-9TyFW_DzSjuTRdRxbRhqjRIx2ASw536VkTsrX6hoCjz0QAvD_BwE&gclsrc=aw.ds

(edit: sorry that links the wrong page you have to click “véhicules neufs” to see the complete range)

They don’t make lightwieght aero-efficent cars anymore. They call them all SUVs and most of them are a CO2 disaster compared with an 80s Citoën AX.

And the Scx of the two vehicles Drac?

the E Golf is Scx .62 I can’t find Audi admitting the Scx of the E-Tron anywhere.

This might be of interest to people:

http://johnhwman.free.fr/Divers/Comparatif_VE.pdf

People buying SUVs is not the same as cars being more aerodynamic.

Whilst I don’t expect to see F1 style cars on the road,

Well F1 cars are not very aerodynamic at all. They’re all about generating as much downforce as possible and downforce generates drag – and lots of it. They’re all about cornering. Look at an Indy car in oval track mode and you’ll see the difference between that and an F1 car in terms of how clean the exterior of the car is. OK they’re playing by different rules and alot of F1 silly bits of appendages are not allowed, but they have alot more of that stuff when in normal circuit configuration or street circuit configuration so in oval track configuration they downforce generating features are significantly dialled down to reduce drag.

Modern cars are aerodynamic. Their coefficient of drag are very good. You’re limited somewhat because you have to have holes in the front for radiators and stuff that you don’t need on EV’s, but compared to CofD’s of cars from the ’70’s and early ’80’s they’re much more aerodynamic despite their larger size. Modern cars have things like panels on the underside of the car to smooth the airflow under the cars. They have much better suspension that keeps the body under control alot better and therefore in a more aerodynamic position. Windscreens are raked back due to transversely mounted engines shortening the front of the car. Much tighter panel gaps and constructed in a way to minimise the number of panels on the car and therefore panel gaps. Flush window seals, windscreen wipers hidden behind the bonnet etc. Your car is brisling with features that are aero-optimised and far more aerodynamic than an F1 car. Also alot of the latest cars have moving louvres to block out the air intakes at the front of the car too so when cooling is not needed they can close up.

SUV’s are not that less aerodynamically efficient than normal cars. They are higher up but they are have more ground clearance, so a bigger gap under the car and alot more air under the car so the frontal area is not actually that much greater than a similarly sized non-SUV. My wife X3 has a similar CofD to a normal similarly sized car. Can’t remember the numbers but did look it up a while back and was surprised.

The thing that has driven the physical size of cars and their weight to increase is not interior space but crash regulations. But despite that thanks to more efficient engines and aero cars are much more efficient than those of 20 or more years ago.