While a drink or two with dinner will slow down your absorption of alcohol compared with drinking alone, you will remain impaired for a longer period.
Dr. Stefano Di Bartolomeo's research team at the University of Udine in northeastern Italy found that one or two drinks with a meal within the six hours prior to driving more than doubled people's chances of being in a accident, and more than two drinks tripled their risk, compared with not drinking.
The risk is increased by three times when drinking is combined with sleep deprivation (less sleep than usual in the 24 hours before driving).
The researchers conclude that people should totally avoid alcohol before driving.
Di Bartolomeo, S., Valent, F., Marchetti, R., Sbrojavacca, R., Barbone, F. "A case-crossover study of alcohol consumption, meals and the risk of road traffic crashes." BMC Public Health 9:316. 2009.