Yeaaaah probably. But I have doubts on what they expected to happen, kab00m á la hollywood sfx and a large crater is what I suspect they were thinking.
If it wasn't for the fact that they have more doctorates than I do I'd say they were utter cretins.
If they'd done something like ummmm.... strip the back of a
delivery van, put some kind of large inflatable sheep in there or even several inflatable mattresses and have those filled with mixed fuel-air, THAT would work.
Naturally the van itself would have its walls pancaked the moment it went off and all large surface areas in the immediate vicinity made of wood or ceramics would get a serious hammering. A brick wall close to it could be caved in by such a large blast and certainly say goodbye to all windows in sight.
Fact is, the best they could have achieved with their carload of petrol is a burning car, which however you look at it is a pretty dam pathetic terror attack. It only happens what, hundreds of times a night anyway?