[viraptor]

Not saying that it's as feasible as normal engine, but when you ride a bike you pretty much fill it with matter that explodes violently when ignited. Then you ignite small parts of it to make the bike move...

We may still see some normal devices which use antimatter in one way or another.

[simpleTruth]

Meaningful amounts of Mater + antimatter produces extreme amounts of radiation, and takes ridiculous amounts of energy to produce.

To put things into perspective, 1kg (~2.2lb) of antimater + 1kg of matter = 2* (9×10^16 J/kg) of energy, TNT = 4.2×10^6 J/kg so that works out to 42,000,000,000 kg of TNT or a 100 mega ton bomb which is larger than the largest H bomb ever tested.

PS: The other issue is unlike gas which is fairly stable, any sort of containment failure = detonation.