Toro Rosso has conceded that hot conditions do not suit their car after finishing outside the top 10 in Hungary.
Jean-Eric Vergne was twelfth, with Daniel Ricciardo a position further back in thirteenth place.
"A difficult race for us, as it highlighted what appears to be our weak point at the moment, namely racing in hot conditions and with track temperatures exceeding 50 degrees, this was the hottest Grand Prix of the year," said team principal Franz Tost.
"The opening stints were tricky on both cars, but towards the end, we picked up a bit more pace which saw us close on the Saubers and Force Indias. Hopefully, when we return to race in cooler conditions, we can once again get back in the points. However, there will be more hot races, so we must investigate ways of improving our car for these conditions."
"Right from the start, it was clear we weren’t really quick," added Ricciardo.
"I tried to hold position as long as I could but we were way too slow. I tried my best in terms of trying to maintain a good pace and look after the tyres, but today it was not enough to go looking for points. We got a bit more out of the car in qualifying yesterday, but it’s hard to repeat that for seventy laps. We struggled at Nurburgring as well, so the heat has got something to do with it."