Driving is generally not a good idea to do in Stockholm but sure, there are worse places. It is just that parking is terribly expensive and hard to find, and as I have mentioned in another tip, there is no ring road, so the infamous Essingeleden takes a lot of heavy E4 traffic right through the city even though much of it isn't even bound for Stockholm and just need to move from north to south or vice versa.
Roads are very good and one can go really fast (225km/h) and get a really kick out of it but there are plenty of cameras on the way, be careful and remember that is better to lose a minute in your life than your life in a minute.
We still missed our flight...
Flying with Ryanair is a guarantee of low prices but sometimes the airport is very far from your final destination so we've rented a car to go from Vasteras to the capital and back and the price was something like 90Eur for the weekend what I didn't find that expensive as the car gave me extreme pleasure driving.
In the mornings and evenings the traffic in the centre of Stockholm can be quite heavy. If you are not used to the Stockholm traffic, try to avoid driving in Stockholm city between 8 and 9 in the mornings and 16 to 18 in the evenings. It can be a bit stressful and it's easy to get lost when not having time enough to read the signs.
RENT A CAR, AVIS, BUDGET, EUROP CAR & HERTZ
CAR RENTAL Numbers in Stockholm: Avis: 020-78-82-00, Budget: 08-411-15-00, Europ Car: 020-781-180 & Hertz: 020-211-211