The following are using EPA combined MPG and the manufactures MSRP. I tried to pick the best MPG comparison and matched options as best I could. The Prius and Escape are no brainers, just buy the hybrid. The Altima and Camry (Camry not shown, but it is almost the same as the Altima) may take a little thought. The Civic Hybrid does not make sense to me, because the cost is close to the larger and better MPG Prius.

Escape Hybrid 4wd: $28,920 (28 MPG)
RAV 4 auto 2.4 4wd: $28,087 (22 MPG)
Break even in 21,380.333 miles at $4.00 per gallon

Prius: 28,516 (46 MPG)
Altima 2.5 S with SL Package: $26,230 (26 MPG)
Break even in 47,320.2 miles at $4.00 per gallon

Escape Hybrid 2wd: $27,170 (32 MPG)
RAV 4 auto 2.4 2wd: $24,661 (24 MPG)
Break even in 60,216 miles at $4.00 per gallon

Altima Hybrid: $30,205 (34 MPG)
Altima 2.5 S with SL Package: $26,230 (26 MPG)
Break even in 109,809.375 miles at $4.00 per gallon

Prius: $25,551 (46 MPG)
Civic 1.8 auto: $17,432 (36 MPG)
Break even in 336,126.6 miles at $4.00 per gallon

Civic Hybrid: $23,352 (42 MPG)
Civic 1.8 auto: $17,432 (36 MPG)
Break even in 372,960 miles at $4.00 per gallon