> most cars are more aerodynamic in reverse than they are going forwards
I tried to find more about it, but I could only find two sources. The first was a Mythbusters episode about a particular Porsche, and the second was a Top Gear episode about a different car. Can you point me to an article that substantiates this?
If you taper properly before the flat cutoff a squared off back (Honda insight is the quintessential example) is fine because the real turbulence happens a few feet behind the vehicle. At speed a blunt (even if it's rounded) nose just isn't great no matter how you cut it but with careful attention to corners, shape transitions and whatnot you can mitigate that quite a lot (modern crossovers with their bulbous front bodywork make heavy use of this).
This is a subject with a million gotcha's that add up to a lot. Be weary of anyone peddling rule of thumb solutions.
Here's one data point, merely removing the rear spoiler an SUV has the same drag in reverse as it does going forwards: https://airshaper.com/blog/mercedes-eqc-drag-coefficient
If the same car had the fine details massaged for the reverse direction in a similar way to how they had already been done for going forwards (i.e. instead of the rear spoiler, putting a similar spoiler facing the opposite direction at the front of the car), the Cd would be significantly less in reverse.
I'd love to get it running again but cant find decent instructions for swapping the battery system out for a normal alternator and battery.
Bikers do this too BTW if you follow the sport, makes for interesting team type tactics.
There is some thought that automated road convoys of trucks following closely might generate fuel savings this way as well.
Funny, my current car does 24 mpg on the highway at the speeds I like. Half the efficiency and probably mostly due to me.
Here's a study which pretty much confirms my idea of slightly rounding off the nose would be the best thing https://www.transportenvironment.org/wp-content/uploads/2021...
Image here: https://ibb.co/FgZvz6p
The article itself states there are bigger benefits to be had modifying the trailer:
"Further aerodynamic improvements are possible, notably on the trailer. For example aerodynamic add-ons, such as tails and side wings, could help deliver even higher significant fuel savings. Their potential is explored in another T&E briefing. [23]"
The referenced article: https://www.transportenvironment.org/wp-content/uploads/2021...
That article shows a variety of tail modifications which have higher effectiveness than rounding the front.
Think a typical "teardrop" airfoil shape, they are blunt at the front and gently taper off at the rear.
In fact most cars are more aerodynamic in reverse than they are going forwards for exactly this reason - on most cars the front end comes in more gradually (the hood portion comes in first, then enlarges to the passenger section) whereas the rear end is usually much blunter (to maximize storage space).