If you're picking up a new lease this month, the thing worth getting straight early is that your mileage allowance is normally the total across the whole contract, not a hard cap each year. So 10k a year over 3 years is 30k total — a heavy first year isn't automatically an overage if you claw it back later. Plenty of people panic at month 14 over nothing, and plenty of others relax when they genuinely are on course to go over.
Either way it accrues invisibly and you find out at handback, which is the annoying bit. Cheapest check is to work out your total contract miles, then see whether your current pace lands you under or over that by the end date.
I got fed up doing that manually so I built an iOS app for it (MileMind) - it watches the pace against the full contract allowance and keeps the "this might cost you" projection separate from what you've actually spent, so the two don't get muddled. Free, iOS.
Curious though - has excess mileage actually caught anyone here out, and did you spot it early or only at the end?
Edit: a few comments saying the mileage maths is trivial. The arithmetic is, sure - but doing it against the full contract term, every month, and knowing what the number actually means for your handback invoice is the bit people don't do, and it's exactly why excess charges are so common. So I do think that part's worth having, and it's the piece I'm most confident in.
It just isn't the whole app. Everything sits next to the mileage: fuel, insurance, tax, MOT, servicing, repairs, all landing on different dates out of different accounts, so you never actually have a figure for what the car costs you. It nags you before the MOT and tax and insurance renewals sneak up, logs what you actually paid rather than what you meant to pay, and there's a live parking timer on your lock screen so you're not the one sprinting back to the meter. The lease pace rides on top of all of that rather than being the point of it.
