The fact that you can use three at once is actually printed on the back of a voucher I just obtained from a work colleague too, by the way, which is nice!
Anyway... this leads me to a great idea.
Everyone - buy Tesco fuel vouchers from your work colleagues, friends and family!
I'll give an example...
A fill-up at 137.9p per litre costs me around £100.66.
With a single 5p off per litre voucher the same fill-up would cost me £97.02.
That's a saving of £3.64 for EACH voucher I use. With three vouchers, for example, I would save £10.92!
Therefore, if I buy a Tesco fuel voucher off a work colleague for £3.63 or less, I've made a profit (as long as I fill up with the same amount of diesel, or more)!
My work colleague normally fills up her tiny little car with £40 or so of petrol. She therefore saves around £1.50 - £2.00 depending on how much fuel is put in because of the voucher.
I therefore met in the middle, as it were, and bought it for £2.50.
My work colleague has now profited even further than the voucher would allow by between 50p and £1, and I have also saved an extra £1 on my next fill-up!
Plus, my work colleague doesn't have to "Pay at kiosk" any more either, she can just "Pay at Pump" and get through faster.
We all win apart from Tesco's!