They're lemons.
The golden rule for buying used cars is, if you can't afford two of them, you can't afford one. The theory behind it being that you might need to spend up to the same amount as the purchase price on maintenance and repairs.
Well for Jaguars, I'd say the rule applies to buying brand new at the dealership, you better make sure you've got enough to buy two from the dealer because you're going to end up needing that much to keep fixing it up when it breaks down