[aerohead]

I went back through Hucho's 2nd Edition. It's all I have by him. Early in the book he mentions forces,moments,directional stability,lift,pitching,wheel loads,and reports that lift has only a small effect,even in cross-wind.....the wheel loading reduction small in relation to static loading....directional stability hardly affected by lift. (Spirit-I, @ Cd 0.2675,and 130-mph,generated -30-lbs downforce at the front axle, and +22-lbs lift at the rear axle,with a travel weight of 4,220-lbs,and 50-50 weight distribution).At posted speed limits and up to 108-mph Spirit is rock solid.
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Hucho mentions high speed sports cars needing spoilers.And he mentions racing cars needing spoilers and wings.
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For RV travel trailers there's mention of leading edge radii producing yawing moments.This is from early research. Emphasis is placed upon percentage of trailer weight placed on the tongue/gooseneck/fifth-wheel,and tow-bar length.Suspensions are different now. Tires are different now. We now have anti-sway technology to deal with cyclic oscillatory vibrations.
Porpoising (pitching) can be addressed with aftermarket fairings.
Some states provide active roadside electronic signage, plus radio broadcasts linked to NOAA,providing weather and wind advisories for high profile vehicles.
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Civil engineers can offer windbreaks, barriers, fencing, landscaping, etc., to mitigate side-wind gust situations.
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Later in the book,Hucho discusses tuning the vehicle nose for a forced flow separation above wind angles above 10-degrees to control yawing moments.
Kamm tail truncations are oblivious to crosswind perturbation.
Fins can be used,however better to just design more body behind the rear axle.
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Further on 'fast' coupes and sports cars and spoilers are fleshed out.Ditto for racing cars.
The greatest challenge is the driver. Reaction times before the car 'notices' feedback from the driver is 0.8-seconds,around 4-car lengths in my truck at 100-km/h.
Unless you've attended racing school, you've never had driver education.
Side gust is the most dangerous situation for Barbie and Ken.It took me one overpass on HWY-385,between Rosamond and Lancaster, California to learn that a Karmann Ghia would change lanes after bridge abutments,during crosswinds.
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The 2019 McLaren Senna has fully-computerized active aerodynamics which will take feedback from throttle,steering,and braking to control the highest downforce of any production road car in order to keep the driver alive.
Going back to the discussion of the F-1 Coanda wing,McLaren says the most dangerous thing about their Senna would be to 'slide' the car, as it would kill the downforce necessary to survive the g-loading in curves.
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G.E.Lind Walker published about cornering stability at high speed in 1950.
Chrysler Corp. began wind tunnel testing for stability in 1957.
Ford Motor opened their first wind tunnel in 1958,conducting stability tests on sedans,the Ford GT40,Indycars,and Dragsters.
In the late 1950s,General Motors basically took over Cal Tach's GALCIT wind tunnel,testing lift,yaw,drag.
In 1960,MIRA opened their wind tunnel for stability testing.
In 1968,Chrysler used the Lockheed,Georgia tunnel to prove out the Charger Daytona.
Car companies never considered lift to be an issue for passenger cars, just high speed sports cars and race cars. Walter H.Korff designed Goldenrod for 555-mph.The Summers Brothers reported that directional stability was never an issue with the car ,which they took to 409-mph,average 2-way run,and as high as 425-mph.Jet cars ended further interest in the project. Now we're over supersonic velocities.
I'm not anxious to see any member have a Darwin moment, however, if driving speeds are kept to posted limits, there's a likelihood that directional stability will be a problem lost on most drivers.