The Toyota Yaris Sol 1.3 L gas model is an excellent small car in terms of:
1. gas usage, as it is quite low (e.g. 1.3 L VVT-i consumes only 5.3 liters per 100 km outside cities, 7.2 liters per 100 km inside cities, and 6.0 liters per 100 km combined)
2. German car tax, as is quite inexpensive being category EURO 4
3. Safety, it received 5 stars from the Euro-NCAP - very few other cars in its class receive such a good rating (see the euroncap.com website for more details), and it has 6 airbags.
4. Price, e.g. a Yaris Sol currently available for approximately 15,000.00 EUR.