Even with same size tires those things still flip fairly easy? You ever ride a 3 wheeler in real life. VERY easy to roll.
Depends on the layout, and the centre of gravity.
As you've noted, the Elio would be more stable. It's a tadpole 3-wheeler rather than a delta 3-wheeler, for a start - there's a caster effect to the rear wheel that gives it some inherent stability. The front track also appears fairly wide, and the tyres look narrow enough that it'd understeer before it digs in.
All a bit like the Morgan 3-wheeler, which never feels even slightly unstable (though I'm sure could do some silly things in extremis). The Morgan benefits from having its engine out over the front wheels, and it being very low indeed - the centre of mass is comfortably low down and far forward.
Delta 3-wheelers are... a bit more tippy. The centre of gravity moves forward when braking, with only one wheel to support it. Not only is there not a lot of braking grip, but any movement of the steering will rock the tyre off its contact patch. The Reliant Robin/Regal/Rialto/etc have a bit of an unhappy mix - narrow track, front-mounted engine (front-mid really, but it's still front-biased), and delta configuration. The Top Gear segment was a bit silly but not beyond the realms of possibility, and the thing would be very unpleasant indeed in windy weather.
Of course, it's not really a car designed for long journeys, and provided you take it easy then they're incredibly frugal and easy to drive around town (if you don't mind hitting every pothole since what the front wheel misses one of the back wheels will hit...).
And styling-wise, I still think the Bond Bug is mega.
Makes the Elio look a bit contrived and soulless.
And lest we forget, the Bond Bug was actually made and sold. The Elio... has been around for about three years now and there's no indication yet that any of the deposit holders will actually get a car.
