Real interest? You mean something like LIBOR + 4%? LIBOR is something like 0.6%, so you're talking 4.6%, with the chance it will go UP.
If so, I wouldn't bother. Not worth the risk. Heck, it's not worth the hassle even if it's 4% fixed (imo) due to the small amount.
Around here, the recent rule of thumb has generally been "pay off debts 5% or higher, then invest" because you can expect over the long term to make more in the US stock market than the interest.
For example, my mortgage is 2.5%, fixed for another 7 years. That's cheap money, half of what the "rule of thumb" would be. Lots of margin. Therefore, I feel no inclination to pay off the mortgage any faster than I have to.
Finally, your payoff schedule is whacky. Did you mean 73€/month, not 730€? Or did you mean a 50k loan, not 5k?