I ran BFGs for quite a while on my pickup and they didn't really give much of a hit to fuel economy at all. They were, however, horrible tyres certainly for UK use as they were completely useless on anything wet be that wet roads, wet snow, wet mud, wet stony tracks, wet grass etc. Also what little grip they did have seemed to decline quite rapidly with very little wear. People who get 50,000 plus miles out of them must be driving indoors, mine went in the bin with way more than legal tread on them and I was only too glad to see the back of them. All the BFG marketing for them seems to feature deserts and Baja and stuff like this so it may be that the are good in dry conditions and I'd not question that they are robust but I think they are extremely old technology, unsuited to UK use, trading on a name they made when they were just about the only AT on the market.