150
about 5 and a half hours
There is 743 miles between Calais, France and Genoa, Italy. The drive would take about 11 hours to complete by car. Flying would take about an hour and a half.
"About 18 hours" was the answer here. Having done this trip many times, I'll expand that a little. If you pick your time of travel with care, use the toll roads, and stop only for fuel, then 15 hours is achievable. This is what I prefer to do: depart Calais 0200, arrive Barcelona 1700. However, this is not exactly a relaxing journey and it can be a hard drive. If you prefer something more relaxing then 18 hours is probably too little to allow. I believe that coach services allow double this.
15 Hours non stop
There is 30 miles between Calais, France and Dunkirk, France. The drive would only take about 40 minutes by car.
In an average car, you would need about six liters of petrol to drive 38 miles. This is equal to about 1.5 US gallons.
300 dollars
The distance (according to Google Earth) is 1,353km and would take about 13 hours 41 mins to drive.
This is a 1,030 km drive for a Calais-Marseille trip, or 1,160 from Calais to Perpignan on the Spanish border. That makes it a 10H30 trip to Marseille, or a 11H30 trip to Perpignan, not including any stops.
15 billion miles
If you mean in france: Approx 10hr and 36 minutes according to google maps
There is approximately 41 miles between Lloret de Mar, Spain and Barcelona, Spain. It would take an hour to drive by car.