Discounting is back with a vengeance in the UK new car market, with some seemingly incredible deals available on certain models. Yet look closer and you will see that there's plenty of smoke and mirrors at play.

Vauxhall tops the discounting charts with an average discount of 17.5% across its model range, according to data from What Car?'s team of Target Price mystery shoppers.

As our deep dive into Vauxhall shows, these discounts are far greater than the 8.2% on an average Vauxhall this time last year; yet since then, Vauxhall has significantly increased its prices.

The upshot is that in net cash terms, the average Vauxhall is actually £213 more expensive than this time last year.

These Target Price discounts include dealer margins and manufacturer finance deposit contributions to PCP finance deals on new cars, but lower monthly payments can then be achieved by a manufacturer increasing the guaranteed future value (GFV, the set price for a balloon payment at the end of a PCP deal) of a car and by making changes to the APR of a finance deal.

The former has been done by Vauxhall, which means that while the cash price might be marginally higher than this time last year, the average four-year PCP payment has fallen by £23 per month to £311.

It's a complicated business, but it illustrates just how many different levers car manufacturers can pull when it comes to influencing the price you pay for your new car: dealer margins, manufacturer deposit contributions, APR rates and GFVs. It can also cut list prices, but this is very risky for residual values, and also inflate or deflate the price of a trade-in.

Take a Vauxhall Mokka Electric as an example: in cash terms, you can get a whopping £9278 off one by taking from the dealer margin and benefiting from a manufacturer deposit contribution, but an average monthly payment is only £21 less than this time last year, despite the percentage discount having increased from 7.2% to 23.7%. The list price has gone up by more than £4000 in that time.

Vauxhall Mokka e