Well, it’s something of a reincarnation for the Chrysler group this time around as the latest model incorporates a Hemi V8 engine.

This is not the Hemi engine of old however, it has this really cool system on board that while it is also not new, it certainly goes a long way to easing the prospect of financial pain that is generally associated with running a V8 petrol.

Jeep calls it Multi-Displacement System engine technology.

Multi-Displacement System (MDS) technology basically shuts down four of the Hemi’s eight cylinders when they’re not needed.

This is good news – many’s the time I have been sitting at traffic lights in a big eight and watching the fuel gauge dropping while some brainless berk queues across (ie blocks) an intersection!

According to Chrysler, the MDS technology reduces overall fuel consumption by up to 20% and there is no noticeable difference to the driver as half the engine switches itself off and on again as required.

But as to the rest, some of you might be wondering what all the fuss is with this Hemi engine thingy?

So here’s a little Hemi history:

Hemi takes its title from the hemispherical design of the combustion chamber and this is technology that Chrysler put into production in the 1940s.

There is some confusion as to who actually first came up with the Hemi design and from what we can gather, Chrysler was not the progenitor of the technology, it just happened to use it most successfully.

Interestingly, the Hemi engine wasn’t really used in cars until after World War II. Talk to any aircraft buff and they’ll likely tell you that the Hemi was most famously tested in the P-47 Thunderbolt, a bomber escort which, in production, ran a 2800 cubic inch radial engine that developed 2300 horsepower. It gave the plane a top speed of 439 miles an hour at 15,000 feet.

By building a V16 Hemi engine and installing it into the P-47, Chrysler managed to get the Hemi-powered plane to break the 500 mile an hour barrier. No one thought it was possible for a piston engine to achieve that speed in level flight.

Flat out and radar tested, the P-47 made 504 miles an hour, making somewhere in the area of at least 3000 horsepower, and likely closer to 3500.

Just to be sure, the test P-47 went out the next day with a different test pilot and again level at 15,000 feet, went through the 500 mile an hour mark. However, only the one engine was ever built. The important thing to keep in mind about this engine is that it was a Hemi headed, push rod valve activated type.

After the success of the Hemi engine had been proven in a wartime application – despite the fact that the Hemi P-47 was never combat proven, – thoughts again turned to Hemi engines in cars.

English company Healey was producing what was arguably one of the best engines for passenger cars with a push rod, twin cam, overhead valve and hemispherical combustion chambers. The engine demonstrated attributes which went against accepted performance in that the Hemi head limited ‘knocking’ and offered better volumetric and thermal efficiency.

Other benefits could be found in the positioning of the intake valve – close to the manifold and carburettor, and the 58 degree angle of the exhaust valve which offered excellent efficiency in the burning of exhaust gases and thus extended valve life.

The Hemi head was easily adapted to a Chrysler engine and found to be considerably smoother than the conventional flathead 6 of the day and it could run easily on the 80 octane fuel which was standard at the time, while demonstrating significant increases in power. All of which was fine for the 6 cylinder engine – the V8 version however, had to compete in a very aggressive market, with Chrysler taking a second seat to Ford in the production stakes at the time.

Added to which, internal pressures within Chrysler made the production of a V8 rather difficult "we only build straight engines, none of this Vee stuff for us, thank you," seemed to prevail in the hallowed halls of design at the time.

Fortunately for Chrysler, there was a ‘fifth column’ that was looking out for the company’s future and the successful V8 Hemi was apparently launched around 1948 under extremely rigorous testing regime which included the clause of no major parts to be replaced, such as bearings, valves, pistons, and rings, at anything less than 100,000 miles. And given that this was Chrysler’s first overhead cam engine, one of the most significant problems to overcome was premature camshaft wear.

This and many other problems were resolved successfully by Chrysler’s engineers and the Hemi engines started to make an impact on the competition scenes of the time. In 1952, Chrysler Hemis were considered Kings of Speed, up against Cadillac and Oldsmobiles, who were both hot on the heels of the Hemi performance title.

1954 saw a milestone reached by Chrysler as it invited the first four finishers of the Memorial Day 500 race to christen a 4.7 mile long oval track at Chrysler’s proving ground, Chelsea.

A Hemi A311 went past the pits and timing stand on its second lap at full cry touching 182 miles per hour.

Five years of intense competition racing followed, but in 1959, the first generation Hemi V8s all but died, but left its legacy in high performance racing.

It’s said that the Hemi headed Chrysler based V-8 engine is solely responsible for virtually all the drag racing records in the world. You cannot compete in the top fuel categories in any class in the IHRA or the NHRA unless it is a Hemi V-8.

And as far as the Hemi of today goes?

Well, the 5.7 litre Hemi used in the Grand Cherokee puts out 240kW at 5000rpm and 500Nm of torque at 4000rpm posting a 0-100km/h time of just over seven seconds.

Long live the Hemi! l