The month-end numbers every small car dealer should track are eight: average days in stock, gross profit per vehicle, stock turn, aged stock percentage, enquiry-to-sale conversion, lead response time, prep cost per vehicle, and cash tied up in stock. Each one is a simple sum you can do in ten minutes from your stock book and enquiry list. Tracked every month, together they tell you whether you are buying well, pricing well and selling well.
Below is each number with its formula and a worked example. The example dealership is made up, and so are its figures. They are there to show the arithmetic, not to suggest what your numbers should be.
The example dealership
Our hypothetical dealer had this month:
- 22 vehicles in stock at the start of the month, 20 at the end
- 12 vehicles sold
- 160 enquiries received
- Total gross profit on the 12 sales: £16,800
- Total prep spent on the 12 vehicles sold: £7,200
Keep the same definitions every month. A number that is worked out differently each time cannot show you a trend, and the trend is the point.
1. Days in stock
What it tells you: how long your money sits on the forecourt before it comes back.
Formula: for each vehicle sold, count the days from the date it came into stock to the date it sold. Average days in stock = total days for all vehicles sold ÷ number of vehicles sold.
Example: the 12 vehicles sold this month spent 456 days in stock between them. 456 ÷ 12 = 38 days.
Look at the vehicles still in stock too, sorted oldest first. The average for sold vehicles tells you how quickly things sell. The oldest unsold vehicles tell you where the problem is.
2. Gross profit per vehicle
What it tells you: what each sale actually earns before overheads.
Formula: for each vehicle, gross profit = sale price − (purchase price + prep + other direct costs such as transport, warranty and admin). Gross profit per vehicle = total gross profit ÷ number of vehicles sold.
Example: £16,800 ÷ 12 = £1,400 per vehicle.
Two things to watch. First, use the real costs. If prep or transport never gets recorded against the vehicle, the profit looks better than it was. Second, if you are VAT registered and use the VAT margin scheme, HMRC's guidance says VAT is due on the difference between what you paid for the vehicle and what you sold it for, and prep does not count towards the purchase price (gov.uk: Using the VAT margin scheme for second-hand vehicles). Track profit after that VAT as well, because that is the figure that pays your bills. This is general guidance, not tax advice.
The free car dealer profit margin calculator shows gross profit, margin and markup for a single vehicle if you want to check one sale.
3. Stock turn
What it tells you: how many times you sell through your average stock in a period. A higher turn means your cash comes back to you faster.
Formula: average stock = (vehicles at start of month + vehicles at end of month) ÷ 2. Monthly stock turn = vehicles sold ÷ average stock. Multiply by 12 for a rough annual figure.
Example: average stock = (22 + 20) ÷ 2 = 21. Monthly stock turn = 12 ÷ 21 = 0.57. Annualised, that is roughly 0.57 × 12 = 6.9 times a year.
Some dealers prefer to work stock turn out by value, using the cost of vehicles sold divided by the average value of stock at cost. Either method works. Choose one and keep using it.
4. Aged stock percentage
What it tells you: how much of your forecourt has stopped moving.
Formula: aged stock % = vehicles in stock longer than your chosen limit ÷ total vehicles in stock × 100.
Example: you set your limit at 60 days. At month end, 5 of your 20 vehicles are older than that. 5 ÷ 20 × 100 = 25%.
The limit is your decision, based on what you sell and how fast it usually goes. What matters is that it is written down and every aged vehicle gets a decision: reprice, refresh the advert, or sell it to the trade. Decide your price-cut steps and your trade cut-off in advance, so the call is quick.
5. Enquiry-to-sale conversion
What it tells you: how well you turn interest into sales.
Formula: conversion % = vehicles sold ÷ enquiries received × 100, for the same period.
Example: 12 ÷ 160 × 100 = 7.5%.
Count each customer once, even if they called and then emailed. If conversion falls while enquiries hold steady, look at how enquiries are being handled. If enquiries fall, look at your prices, photos and adverts.
It is worth splitting this by source too. A marketplace that brings plenty of enquiries but few sales is costing you more than its listing fee suggests.
6. Lead response time
What it tells you: how long a buyer waits to hear back from you after they get in touch.
Formula: for each enquiry, the time from when it arrived to your first reply. Use the median, the middle value when you line them all up, rather than the average, so one enquiry left over a bank holiday does not distort the figure.
Example: you line up this month's 160 response times and the middle value is 47 minutes.
Look at it in two halves: inside opening hours and outside them. A quick daytime response with slow evenings and weekends usually means the problem is cover, not effort. Buyers browsing on a Sunday night are often contacting other dealers at the same time.
Keeping every enquiry in one place makes this much easier to measure. Enquiry management in a DMS brings enquiries together so nothing is left in someone's personal inbox.
7. Prep cost per vehicle
What it tells you: what it costs to get a vehicle ready to sell, and whether you are buying vehicles that need too much work.
Formula: prep cost per vehicle = total prep spent on vehicles sold ÷ number of vehicles sold.
Example: £7,200 ÷ 12 = £600 per vehicle.
Look at the spread as well as the average. If most vehicles cost a few hundred pounds to prep but two cost over £1,500, look at where those two were bought and what was missed at appraisal. Count in-house work at a proper cost, or this number will flatter you. A preparation board that keeps a running prep cost on each vehicle means the figure is already there at month end.
8. Cash tied up in stock
What it tells you: how much of your money is sitting on the forecourt right now.
Formula: cash tied up = for every unsold vehicle, purchase price + prep and other costs spent so far, added together.
Example: your 20 unsold vehicles cost an average of £8,050 each including prep. 20 × £8,050 = £161,000.
Then split it. If the 5 aged vehicles account for £38,500 of that, you know exactly how much cash is stuck in stock that is not moving, and what selling them would free up for stock that does.
Putting it on one page
Our hypothetical dealer's month-end sheet:
| Number | This month |
|---|---|
| Average days in stock (sold vehicles) | 38 days |
| Gross profit per vehicle | £1,400 |
| Stock turn | 0.57 a month (about 6.9 a year) |
| Aged stock (over 60 days) | 25% |
| Enquiry-to-sale conversion | 7.5% |
| Median lead response time | 47 minutes |
| Prep cost per vehicle | £600 |
| Cash tied up in stock | £161,000 |
On its own, one month tells you little. Put three months side by side and the patterns appear: profit per vehicle drifting down as prep creeps up, or aged stock rising while conversion holds, which points at buying rather than selling.
You can keep this sheet in a spreadsheet. If your stock, costs, enquiries and sales already live in a dealer management system, most of it is already worked out. The Vehiso DMS shows days in stock, purchase and prep costs, stock turn and enquiry sources from the same records you use every day, and it is included on every Vehiso plan, including the Free plan for up to 5 vehicles. Our guide to stock and sales reports explains how to use them.
Frequently asked questions
What is the most important number for a small car dealer?
If you track only one, track days in stock alongside gross profit per vehicle. Together they tell you how much each sale makes and how long your money was tied up making it. A vehicle that makes slightly less but sells in half the time often does more for your cash.
How do I calculate stock turn for a car dealership?
Divide the number of vehicles sold in a period by your average number of vehicles in stock over the same period. For a month, average stock is the opening count plus the closing count, divided by two. Multiply a monthly figure by 12 for a rough annual figure.
Should gross profit per vehicle include prep costs?
Yes. Gross profit per vehicle should take off the purchase price, prep and other direct costs such as transport and warranty. Leaving prep out makes every sale look better than it was and hides vehicles that cost too much to get ready. If you use the VAT margin scheme, track the figure after that VAT as well.
What counts as aged stock?
Aged stock is any vehicle that has been in stock longer than a limit you set yourself, based on what you sell and how quickly it usually goes. Write the limit down and use the same one every month. What matters is that every vehicle over the limit gets a decision, not that you use any particular number.
How long should month-end numbers take to produce?
From a tidy stock book and enquiry list, these eight numbers are simple sums that should not take long. Most of the time goes into chasing missing costs and dates. If your stock, prep and enquiries are kept in one system as you go, most of the work is done before month end arrives.
