Jaguar Mk X and 420G values: the most Jaguar for the money, and the third that do not sell

The Mk X is the most Jaguar anyone can buy for the money. Jaguar Mk10 values, to use the spelling half the sale rooms prefer, sit at a median of £10,688 for the Mk X itself, £7,840 for the 420G and £8,100 for the compact 420, with the whole record of 170 recorded sales running at £8,730 at the median and a middle half of £5,920 to £12,731. That buys the widest car Britain ever put into production, with an E-Type engine and independent rear suspension, for less than a good Mini Cooper. The spread runs from £715 to £48,300.

The catch is in the clearance rate. Only 69.4% of these cars found a buyer, the second-lowest figure on this site, and understanding why is more useful than the median.

The Jaguar Mk X and 420G guide covers the two big saloons, the confusingly named compact 420 and what to check before buying one. This page is about the money.

The earlier car sells above the later one

The Mk X sits at £10,688 across 59 recorded sales; the 420G, which is the same car after its 1966 facelift, at £7,840 across 55. Nearly £2,900 separates two cars that share a shell, an engine and a chassis.

That is a collector’s preference rather than a mechanical judgment. The Mk X is the original, with the purer grille and badging, and it is the name the marque’s history remembers; the 420G reads as the run-out version. If you are buying one to use, the logic points firmly at the 420G, which gives you the same seventeen feet of Jaguar with the same 4.2 XK six for about three quarters of the money. If you are buying one to keep, the market has been consistent about which it prefers.

The other 420, and why it muddles the figures

Fifty-six of the 170 sales in this record are the compact 420, and it is not a big Jaguar at all: it is a different car on the Mk2 and S-Type platform, sharing only a number with the 420G. It sits at £8,100 at the median with a middle half of £4,947 to £12,544, between the two big saloons.

The sale rooms list these cars under overlapping names, so the record carries all three together and the combined median of £8,730 describes no single car particularly well. Read the badge rows rather than the headline. And when a private advert or a price guide quotes you a figure for “a 420”, establish which car it means before you do anything else, because the two are separated by three feet of length and about sixty years of confusion.

A chart with nothing in it

The yearly median ran £9,180 in 2021, £8,858 in 2022, £8,888 in 2023, £11,788 in 2024, £6,100 in 2025 and about £10,559 so far in 2026. That is not a trend, it is a small sample: between 7 and 24 sales a year, spread across three models whose medians sit £2,900 apart, so the mix alone can move the annual figure by a third without the market shifting at all.

What can be said is that in real terms the record is broadly flat over a decade. For a car in the eight-to-eleven-thousand bracket, flat means slowly losing ground to inflation, and the big Jaguars have not taken part in the rises that lifted the E-Type and the Mk2 over the same period. That is the price of being large, thirsty and hard to store.

The third that do not sell

Two hundred and forty-five of these cars were offered and 170 sold. A 30.6% failure rate is the second worst on this site after the Sierra Cosworth, and the cause is different: not optimistic reserves so much as the arithmetic that follows the sale.

A Mk X is seventeen feet long, needs a proper garage, returns mid-teens to the gallon, and costs the same to restore as a smaller Jaguar over twice the area. A buyer doing those sums stops bidding earlier than the seller hoped, and a car that looks like a bargain at £6,000 is not a bargain if its sills need doing. For a patient buyer that is an opportunity, because it means the good cars, the ones where somebody else has already spent the money, are the sensible purchase even at £16,000.

Where the big Jaguars change hands

The regional British sale rooms carry most of the volume and most of the projects, and the American online platforms take the best cars, as they do across the marque. The recent record shows the range: a Mk X at £4,781 and another at £16,000 in Britain, a 420G at £12,647 and a Mk X at £18,135 on the online platforms, and a 420 at £10,559 at a Continental sale. The limousine and wedding trade takes a share of the usable ones outside the sale rooms entirely. Whether a recorded price includes the buyer’s premium varies by sale, which is one more reason to read the usual range rather than any single result.

Insuring, restoring, selling

For an agreed-value policy the Mk X and 420G need separate figures despite being the same car, because the market treats them separately, and a compact 420 needs its own again. On restoration, be blunt with yourself: a full body restoration on any of these costs several times what the finished car makes, and there is more of it to do than on a Mk2. The only sensible project is a dry, complete car with a tired interior. If you are selling, storage is your enemy and the good months are the ones when a buyer can picture using it, and a full history file on a car this cheap is worth more proportionally than on almost anything else.

Related

The Mk X sits above the Mk2 that outsold it and now sells for several times as much, and below the XJ that replaced it and costs about the same. Its engine is the E-Type’s. For the period, see British classic cars of the 1960s. For how all the figures on this site are compiled, see what classic cars sell for.