We've always had a fairly open relationship and this occasion was one of the most memorable. We had been out on the town all afternoon and into the evening drinking and partying with friends. My wife C was wearing black leggings with a short denim skirt and a tight fitting vest top and jacket. Sexy but not too slutty. Towards the end of the evening we decided to head for a taxi home. C phoned the local minicab firm and as usual on a Saturday night there was at least a 45 minute wait. During the wait we got hot and horny with each other and I dared her to take off her leggings and knickers before the taxi arrived. That she did and the conversation turned to teasing the taxi driver! The poor sod has to work a Saturday night and take loads of drunks home after all.... The taxi duly arrived and C climbed in the front seat with me in the back. The driver was a good bit older than us, at least late 50's when we are early 30's. C sat with her legs crossed and the short denim skirt crept further up her thigh. I could see the driver glancing down every now and then and I was mentally begging C to go further. About 10 minutes into the journey home I noticed that C had her hand on the drivers knee and was rubbing up and down his thigh. The conversation turned hot in the front with C saying that I was ok with what was happening. By this time C had parted her legs slightly and the driver would have been able to see her pussy. The driver pulled over at the side of a park not far from where we live. C released his cock from his trousers and it was smallish but thick. C went down on him and started sucking like her life depended on it. I was hard as feck in the back watching what was taking place. The driver was sporting a rather stumpy hard on but C was enjoying it nevertheless. C had now spread her legs wide in the front and the driver had at least 3 fingers inside my wife. He asked if he could fuck her! She was desperate for his cock at this point and he reclined his seat and let my wife straddle him. I was wanking furiously in the back as my wife fucked this older man while looking me in the eye. Before long the driver started groaning and mumbled that he was coming. C squatted as deep as she could to try and get his cock further in her pussy as he came. My wifes face was a picture. She climbed off the driver and as she did his come ran from her pussy and over his legs and seat. It was horny as feck. The driver was lost for words so he pulled up his trousers and drove the remaining 5 mins or so to our street. We didn't have to pay and he gave us his mobile number should we ever need a taxi. I was still so turned on and so was C as she could still feel the drivers spunk running down her legs. We got home and had the best sex ever with me adding another load to that of the drivers.