What are the famous design failure cars?

[Galane]

Robert Q. Riley has figured things out for trikes, both with the single wheel at the front, and at the rear. https://rqriley.com/product/tri-magnum-trike-plans/

There are many kits to make big cruiser motorcycles into trikes, and pre-built versions if you don't want to DIY. RT Trikes (and a couple of other companies) can put two wheels on the back, or on the front, of motorcycles. Scrolling through google image results for motor trike shows a couple of companies are doing conversions where the dual front wheels tilt so the trike can lean into turns.

Search for three wheel vehicle and you'll find ones that aren't built from a motorcycle or scooter, like the Polaris Slingshot and Tanom TC-3.

[freebeard]

Front wheel drive with twin motors and torque vecoring.

If I was designing a super-trike from scratch, it would have three wheel drive and three wheel steering. Would that be excessive?

[redpoint5]

Originally Posted by freebeard

Front wheel drive with twin motors and torque vecoring.

If I was designing a super-trike from scratch, it would have three wheel drive and three wheel steering. Would that be excessive?

The data would bear it out. Measure the various criteria for performance:

Efficiency (Wh per mile on a standardized test)
Acceleration
Cornering G-force (skidpad)
Braking
Total cost of ownership
etc

[Bicycle Bob]

Originally Posted by freebeard

If I was designing a super-trike from scratch, it would have three wheel drive and three wheel steering. Would that be excessive?

Depending on your mission, etc, 3WD could certainly be handy, although 2WD is 50% better than it is on a quad. I'm fond of velomobiles with mechanical drive to the rear wheel, and electrics up front for snowy days.
Three wheel steering is a rare requirement. There was a fad for All Wheel Steering on the road in the 80's, and I thought Honda had the most elegant system, while staying all-mechanical. For a highway lane change, your initial steering input was mimicked at the back, about 50%, so you'd slide over with less yaw than usual. Once the steering angle at the front got past about 5 deg, the back caught up and passed it, so for parking, you'd get a considerably tighter turning circle. The cost/benefit just didn't get a second generation built. In road racing, the driver would have a harder time sensing his angles of drift. Off-road, it might get you through some otherwise impossible places.

One caveat with trikes (except MC sidecar rigs) is that you want to find three smooth tracks among the potholes, not just two, and your middle wheel will be running where few others do.

BONUS: Dodge once put out a pickup truck with a removable roof. Then they went around and asked how the owners liked them. Most had never been off, and a large minority of owners were not even aware that it was removable.

[slowmover]

The Ramcharger?

[Galane]

1989-91 Dodge Dakota convertible pickup. https://www.hagerty.com/articles-vid...rt-convertible

When MoPar tried to capitalize on the fad for drop top small trucks.

[Frank Lee]

My exposure to delta trikes has been good and I've read about successful high-performance deltas so IMHO they are just as viable a configuration as any.

[Bicycle Bob]

The reason I only design tadpole trikes is because I am also trying to conserve space on the road, and won't compromise on turning ability with the brakes on. A safe delta would come out lower and/or wider than I like.
The Harley trike has astronomical insurance rates, and ATV manufacturers went to quad layouts to avoid a wave of lawsuits.

[Galane]

Sale in the USA of ATV trikes was banned from April 22nd 1988. Dealers weren't even allowed to sell used ones. Private owners could still sell theirs. The ban was lifted in 1998 but nobody is going to go back to making them because people were and are mostly too stupid to use them properly. https://thumpertalk.com/forums/topic...ned-from-sale/

I remember one video used to promote the "ATVs are deadly!" campaign. Some dumbass parents put their very young son on the biggest quad made. He took off, hit something. Kid goes flying, the ATV flips a few times, lands upright. The kid got up and ran right back to it.

[Bicycle Bob]

"Every year, we make it more idiot-proof, and every year, they build a better idiot."
- Engineer's Lament

Jeep also got sued for highway rollovers.