A police spokeswoman said two men had broken into a property in Sunnybank Road before stealing keys to the car that was parked outside.
One of the men then drove off in the BMW while the other followed in a white sports car at around 5.15pm.
She added enquiries are continuing and urged anyone with information to contact police on the non-emergency number 101, quoting crime reference J3/18/455.
There was also an attempted break-in during the early hours of Tuesday, March 27, in Field View Road.
The victim said his motion-sensitive door bell went off at 12.10am, following which he opened the landing window and found three men standing by the front door.
He banged on the window and they ran off and got into what looked like a dark coloured Audi A1.
Police were called and have already reviewed the CCTV, he added.
WelwynHatfieldTimes