The RAC says some drivers took advantage of the emptier roads to drive at "dangerous speeds" – including in residential areas.
Department for Transport data shows cars and light vans travelled at an average speed of 30.7 mph on 'A' roads in the city last year – a four per cent rise on the average of 29.5 mph in 2019.
The A1231 Sunderland Highway through Washington saw the biggest rise in speeds – up 20% to an average of 39.1 mph – followed by the A184 Sunderland to Boldon road, which saw average speeds rise by six per cent to 27.3mph.
Nationally, the average speed of cars on 'A' roads rose by eight per cent last year to 27.3 mph – caused by a steady increase in speeds following the Covid-19 stay-at-home restrictions in March last year, the DfT said.
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Simon Williams RAC road safety spokesman, said the impact of the pandemic was "a double-edged sword".
He added: "On the one hand, fewer delays is positive and may well have led to an improvement in overall air quality, but on the flipside, we know that some drivers have taken advantage of quieter roads by driving at dangerous speeds."
Mr Williams said it is important police forces continue to crackdown on excessive speeders and that there are consequences for their "totally unacceptable" actions.
The Department for Transport said average speeds are returning to pre-pandemic levels as Covid-19 restrictions continue to be eased.