Examples (only researched a single bank yet):

1,500€ for 12 months, 1.99% interest per year (1.97% debit interest rate): 126.34€ per month

(However, my calculation of (1500 + (1500 * 0.0199)) / 12 gives me 127.49€; not sure where the difference comes from)

126.34€ per month is too high for me. Increasing it to 24 months:

1,500€ for 24 months, 4.49% interest per year (4.40% debit interest rate): 65.41€ per month

Now the interest rate is quite high imo.

However, the interest rate does not increase if I increase the term:

3,000€ for 60 months (5 years), 4.49% interest per year (4.40% debit interest rate): 55.81€ per month

Also not sure if "debit interest rate" is the correct translation. It's called "Sollzins" in German.