If buying the Prius was according to you, the only way to save the environment then think again, and then again. Or at least read the results that have just been issued by AutoZeitung for the BMW 118d vs Toyota Prius. The results were more surprising than you would otherwise care to imagine. Not only did the Prius offer no clear and distinct advantage except slightly lower emissions but it was outperformed easily by the BMW mixed driving fuel economy thanks to its improved combusiton process and particulate filters.

1st Place: BMW 118d (3,013 points)
2nd Place: Toyota Prius (2,665 points)

BMW 118d / Toyota Prius (points)

Chassis: 590 / 529
Comfort: 647 / 603
Engine/transmission: 678 / 585
Driving dynamics: 650 / 467
Costs/environment: 448 / 481
Total: 3,013 / 2,665

BMW 118d / Toyota Prius (performance)

Weight (kg): 1,374 / 1,300
Consumtion (mixed): 4.9 L (47.9 mpg) / 5.9 L (39.8 mpg)
Lap time: 1:54,2 / 2:05,1
Slalom (km/h): 63,5 / 59,4
0-100km/h: 8.7 seconds / 12,0 seconds
80-120km/h: 6.8 seconds / 11.1 seconds
Hp/Nm: 143-hp/300Nm / 78-hp/115Nm (E-motor: 68-hp/400Nm)
Price (€): 25,300 / 24,877

Source